Milledge Hall, University of Georgia, Athens, GA 30602, USA. DONNA ALVERMANN ... 1997 John Wiley & Sons, Inc. Sci Ed 81:1 â 27, 1997. © 1997 John Wiley ...
Preservice Elementary School Teachers’ Conceptual Change about Projectile Motion: Refutation Text, Demonstration, Affective Factors, and Relevance CYNTHIA HYND Milledge Hall, University of Georgia, Athens, GA 30602, USA DONNA ALVERMANN 309 Aderhold Hall, University of Georgia, Athens, GA 30605, USA GAOYIN QIAN Lehman College, City University of New York, B-20 Carman Hall, Bronx, NY 10468, USA Received 5 January 1995; revised 28 August 1995; accepted 9 October 1995 ABSTRACT: This study investigates changes in preservice teachers’ conceptions about projectile motion brought about by a combination of reading and demonstration and an appeal to usefulness. Participants were either told in advance they were expected to teach a videotaped lesson on projectile motion or that information was withheld. In addition, teachers either participated in a combined demonstration – text or in a text-only group. We randomly assigned 73 preservice teachers with nonscientific conceptions to one of four groups comprised of the two levels of the two conditions (Told/Not Told, Demo – Text/Text only) and documented conceptual change through short-answer, true/false, and application tasks. Additional data were obtained from an interview questionnaire to determine the influence of preservice teachers’ attitudes and experiences on conceptual change. Furthermore, the videotapes and transcriptions of 16 videotaped lessons and postlesson, structured interviews were analyzed to provide information about the interaction of variables producing change and to track the changes in thinking that were made. The results indicated the effectiveness of a combined Demo – Text condition on immediate posttests and effectiveness of text in producing long-term change. Descriptive and qualitative analyses indicated an interaction of instructional, motivational, and knowledge factors; provided evidence that conceptual change proceeds in a piecemeal fashion; and documented that restructuring of knowledge may lead to new nonscientific conceptions. © 1997 John Wiley & Sons, Inc. Sci Ed 81:1 – 27, 1997.
Correspondence to: C. Hynd
© 1997 John Wiley & Sons, Inc.
CCC 0036-8326 /97/010001-27
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INTRODUCTION
Conceptual change in science has been of interest to science educators and other educational researchers for more than a decade. Yet, students still have difficulty learning complex scientific principles, especially if they are counterintuitive, and teachers remain frustrated in their attempts to help students learn them. Indeed, the interactions among a variety of poorly understood influences on learning are, in all likelihood, responsible for the difficulty in effecting conceptual change. Therefore, this study is an attempt to explore the interactions of some of those influences. Recruiting preservice teachers as participants, we combined text with demonstration in one condition, appealed to the usefulness of learning in another condition, engaged the teachers in thinking about their positive and negative experiences, and asked them their opinions about the importance and usefulness of science and their interest in learning it. We evaluated their conceptual change by using paper-and-pencil tests and by listening to their explanations of concepts to an elementary school student. Furthermore, we attempted to trace the teachers changes in thinking over time. The effect of these conditions were evaluated in light of the research and theory regarding the epistemological, cognitive, and affective dimensions of conceptual change. We begin this article with a discussion of the nature of nonscientific thinking, the concept we wished to teach, and the nature of conceptual change — the cognitive task we wished to affect through reading.
BACKGROUND Nonscientific Thinking
Individuals often hold theories about the way the world works in contrast to those held by current scientific thinking; that is, the theories are considered nonscientific by practicing scientists. In this study, we use the term “nonscientific” to mean unacceptable to today’s scientists and the term “scientific” to mean currently acceptable. However, we acknowledge the likelihood that today’s acceptable science will be tomorrow’s naive science. Also, there are shades of acceptability. For example, Newtonian physics is useful in describing easily observable phenomena but inadequate for describing phenomena at an atomic level. Because of the changing nature of scientific knowledge, it is often difficult to know what to call nonscientists’ theories. The way many nonscientists think about the world may have been accepted in an earlier time and appears unimportant in their daily lives. They have no difficulty maneuvering a car, throwing a ball, or doing physical work. Often, it is only the people who need to be precise who rely on scientific principles. Engineers, for example, must rely on the principles in physics to make accurate calculations. If they did not, their buildings or bridges might collapse. But even their calculations could be improved through advances in understanding (note the collapse of many buildings during the Japanese earthquake that were thought to be built using sound physical principles). Therefore, it is for want of a better term that we use “nonscientific.”
The Concept
The scientific idea participants were asked to learn is actually a cluster of ideas that lead one to understand the forces at work when a projectile is put into horizontal motion. If a cannonball is shot from a cannon at the top of a cliff, it continues in an arced path to the ground. If an object that is being carried forward is released, it also continues in an arced path to the
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ground. The paths are the result of two independent but simultaneous factors. As a cannonball is shot, the force of the shot places the cannonball in a state of forward motion at a constant rate of speed. Because a carried object is in motion when it is released, it also continues to move forward at a constant rate of speed. The object’s forward movement is an example of Newton’s law that an object in motion tends to stay in motion. At the same time, however, the object is being acted upon by gravity. Gravity, an outside vertical force, pulls the projectile toward the earth at a constantly accelerating rate. (It accelerates at a rate of 9.8 m/s2.) The object’s movement downward at that accelerated rate is not affected by its movement forward. That is, an object will fall down at the same rate as an object that is simply dropped straight down from the same point. The forward motion does not slow down or speed up gravity. Likewise, gravity does not slow down or speed up forward motion. Although both algebra and calculus can be used to solve problems based on these concepts, in this study, we confined our teaching to these concepts alone. Many people believe that a cannonball will move forward for a while and then begin to deviate downward, saying that the cannonball’s forward motion must be “used up” because it overpowers the effects of gravity until it does. (This theory was accepted thinking before Newton’s time.) Those before Newton did not understand that an outside force is necessary to change a projectile’s motion, believing, rather, that there is a force implanted in the projectile when it is placed in motion that somehow dissipates. In addition, many people fail to ascribe movement to a carried object, because it appears to be at rest to the person carrying it. Therefore, if released, they believe a carried object will fall straight down. They also do not believe that a dropped object will land on the ground at the same time as a horizontally projected object, given identical release times. They believe that the forward motion either speeds up or slows down the vertical motion. They often describe the path of an object, not as an arc, but as straight out and then curved down. These ideas that are inconsistent with Newtonian theory have been described in other research (Duit, 1991; McCloskey, 1983; Hynd et al., 1994). Prior work with high school and college students revealed that more than 90% of this population have nonscientific ideas about motion (Alvermann & Hynd, 1989; Hynd & Alvermann, 1989). Conceptual Change
For individuals who hold nonscientific ideas about the way the world works, learning accepted scientific concepts can be difficult. Researchers (e.g., McCloskey, 1983; Maria & MacGinitie, 1981; Marshall, 1989) have found that individuals whose ideas conflict with new information often disregard or discount the new information in favor of existing knowledge, when it is necessary for their learning to alter existing knowledge. Conceptual change, the altering or reorganization of existing schemata to account for new learning, appears to take place only under certain conditions. These conditions, as of yet, are poorly understood. Researchers have previously described a piecemeal, sawtooth pattern of changes in thinking (Schymansky et al., 1991; Strike & Posner, 1990; Alvermann & Hynd, 1989) when it does occur. Students do not often completely change their nonscientific theories to scientific ones. Also, when it does occur, conceptual change has been hypothesized to be the result of several interacting factors, epistemological, cognitive, and affective in nature. Epistemology. There may be epistemological reasons why conceptual change is difficult. Carey and Smith (1993), for example, say that, developmentally, children move from the idea that knowledge arises unproblematically from observations to an idea that knowledge acquisition depends on one’s interpretive framework, allowing for two or more interpretations of the
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same observations. Kuhn et al. (1988) provide evidence that younger students have difficulty interpreting two conflicting points of view, believing that the “truth” will be found once they observe the facts. We can understand why people with this less mature epistemology find conceptual change so difficult when it comes to counterintuitive science concepts such as concepts about projectiles. Students believe that understandings of the world are direct results of their observations. Students who are asked to explain their hypothesized, but not scientifically accurate, path for a projectile often use common sense based on prior observations to explain them. They have recounted their observations of old World War II movies, for example, when explaining that a bomb dropped from a moving airplane travels backwards from the point of the drop (it actually moves forward). They have said that they have observed a projectile going out for a while and then deviating downward when, in fact, they have merely been unable to detect the slight downward movement of an object at the moment it is placed in motion and the air resistance that slows the objects’ forward motion (Hynd et al., 1994). Because most people have had much success relying on their observations of the world, they believe that these observations are accurate. Without observable outside forces, students believe that inner forces must be at work. Observation plus common sense reasoning equals “reality.” Conceptual change, then, may come about only as people realize that their previous observations and subsequent beliefs about the world are inaccurate. In this realization, the epistemology of observation leading unproblematically to knowledge is challenged. Other research (Hynd et al., 1994) provides some support for this contention. In that study, students who believed that science concepts were complex rather than simple were more likely to learn counterintuitive concepts. Strike and Posner (1990) hold that conceptual change is more likely to take place when students believe that science is logical and useful to them in their everyday dealing with the world. Cognition. There are also purely cognitive reasons why conceptual change is difficult. Hew-
son and Hewson (1983) explain that, when students are confronted with conflicting data, rather than undergo conceptual change, they can discount the data, ignore it, or memorize it (compartmentalize it). Chinn and Brewer (1993), in explaining what scientists themselves do with conflicting data, offer even more ways for scientists to maintain their existing perceptions. In other words, there are more avenues for maintaining ideas than there are for changing them. Often, the path of least resistance is maintenance. Posner et al. (1982) hypothesize that there are four essential conditions for conceptual change. These include: (a) dissatisfaction with one’s current conception, followed by the degree to which the new conception is deemed (b) intelligible, (c) plausible, and (d) fruitful (in the sense that it will provide a framework for the solution of new problems). Conflict between one’s nonscientific ideas and newly introduced scientific concepts is a major component of this scheme. A meta-analysis (Guzzetti et al., 1993) has documented the effectiveness, at least in the short term, of strategies believed to produce cognitive conflict. One such strategy is the use of refutational text — text that refutes common intuitive conceptions in favor on scientific ones. Attitude/Motivation. Conceptual change has also been linked to attitudes and motivation. Gilovich (1991) argues that erroneous perceptions of the world can arise from motivational as well as cognitive sources. Affective conditions influence what kind of and how much evidence is considered in cognitive decisions and will presumably effect what one learns from reading. Strike and Posner (1990) state: “A wider range of factors needs to be taken into account in attempting to describe a learner’s conceptual ecology. Motives and goals and the institutional
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and social sources of them need to be considered” (p. 10). The idea of a “conceptual ecology” that includes motives and goals provides a focus on the underlying factors that interact to cause individuals to maintain a certain view of the world — a view that may be regarded as erroneous by scientists. Pintrich et al. (1993) claim that students are not “child-scientists” and have ego-involved or extrinsic motivations for learning that may not be conducive to conceptual change, in that conceptual change appears to require considerable effort. In one study, we found that students who believe that physics knowledge is instrumentally useful to them are more likely to exhibit intrinsic motivation to learn physics and, hence, are more likely to undergo conceptual change (Hynd et al., 1994). Usefulness, to them, was used more in the sense of being useful to their future careers than it was to being useful in the sense of helping them to more accurately explain physical phenomena, although both were important. In contrast, students who did not undergo conceptual change could think of no use for physics, were not planing careers where they would use physics, and described their motivations for learning physics in ways that were more extrinsic than intrinsic. Unfortunately, for the understanding of counterintuitive physics principles, many students in high school and beyond lack intrinsic or instrumental motivation to learn science.
Instruction
With all of the difficulty involved, what sort of instruction is helpful in inducing conceptual change in students? In another study (Hynd et al., 1994), high school students who read refutational text about the targeted physics principles learned, in the long term, more than students who participated in demonstrations and who talked to each other in groups about the principles. In that study, talking to each other actually appeared to have a debilitating effect on conceptual change. Students were talked out of scientifically viable explanations of phenomena by their peers. Demonstration produced improvements on immediate but not delayed achievement tests, if combined with reading. In a study by Marshall (1989), a combination of demonstration and reading produced the greatest change in subjects’ understanding of the causes of seasonal change. The importance of reading in science instruction has been a debated issue. Although textbooks appear to guide the curriculum and be the mainstay of science instruction (Schymansky et al., 1991; Yore, 1991), their use is often discouraged by science educators, who prefer that teachers engage students in the process of learning science through discovery and hands-on experiences (Lloyd, 1990; Newport, 1990; Osborne et al., 1985). In a metaanalysis, however (Guzzetti et al., 1993), text that refutes common nonscientific ideas proved effective at helping students learn scientific principles that seemed counterintuitive.
The Study
Because one goal was to study complex interactions previously mentioned in the literature that were influences on learning, we collected several types of data, some experimental and some exploratory. For the exploratory data, our intention was to generate hypotheses. We asked five questions. (a) Will combining demonstration and reading enable preservice teachers to overcome their prior conceptions? This question was in response to previous research with younger populations showing that text and demonstration interacted to induce short-term learning, but that only text produced conceptual change over time (Hynd et al., 1994). Deriving similar results from an older, more conceptually mature population would add veracity to our other
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(b)
(c)
(d)
(e)
studies. More robust or different results would provide fodder for discussing the developmental nature of conceptual change. Will telling preservice teachers that they will be expected to teach a concept provide the necessary motivation for overcoming prior conceptions? This question was asked because of Posner et al.’s (1982) caveat that a new theory must appear fruitful in order for learners to reorganize their existing schemata to include it and because of our other research with high school students showing that relevance and usefulness were influences in conceptual change (Hynd et al., 1994). Although we had documented student’s comments about the usefulness of physics in other studies, we had never actually manipulated a usefulness condition. What influences do prior experiences and attitudes have on conceptual change from reading? We chose this question because of researchers (Strike & Posner, 1990; Gilovich, 1991; Pintrich et al., 1993) calls for studies dealing with affective factors such as motivation and epistemology. Another study with high school students found that students’ attitudes toward physics topics and their attitudes toward the structure of their physics classes predicted the learning of counterintuitive information (Hynd et al., 1994). Again, similarities to other studies would provide validity; differences with other studies would allow discussion of developmental effects. What changes in thinking do preservice teachers make as they proceed from being taught a physics principle to actually teaching the principle themselves? Conceptual change is still poorly understood and hypothetical in nature. We were looking for evidence that conceptual change did, in fact, occur, and wanted to document the form it took. What interactions among variables help explain why some learn counterintuitive information from text and others do not? We asked this question because it is important to describe conditions in which conceptual change would be likely to take place — conditions that included each student’s background, epistemology, and attitude as well as cognition. More mature, preservice teachers were especially interesting as a contrast to students in other studies.
While the first two questions were investigated experimentally, the others were not. Observations made concerning the last three questions were exploratory. The differences between this and other studies are threefold. First, we wanted to involve preservice teachers as participants. The reasons for involving preservice teachers was because it is important for teachers to understand the scientific principles they teach and because we wanted to test the idea that they would be more motivated to learn information due to their need to teach it — a type of instrumental motivation (relevance) similar to that felt by an engineering student. Furthermore, preservice teachers are older than the high school students we had involved in studies previously. If Carey and Smith (1993) are right, then, these students should have a more mature epistemology about learning — one that might allow them to change their conceptions stemming from observation of physical phenomena. Hence, they may more successfully undergo conceptual change than high school students would. Second, in this study we asked participants to describe their attitudes toward physics and physics textbooks and the influences in their thinking as a result of their schooling. Although other studies have explored these influences (e.g., Hynd et al., 1994), the fact that these participants were practicing to become teachers meant that they had been primed to think about the effects of schooling on learning as a result of the education courses they were taking. Also, they had taken science, including physics, in college and had more experiences to bring to bear on the questions we asked.
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Third, this study limited the discourse in order to prevent the preservice teachers from talking to each other. The researcher initially talked to each individual preservice teacher. Later, the preservice teacher talked to an elementary school child. Although the learning environment was somewhat artificial, we wanted to limit the solidification or learning of nonscientific information that has been found to take place after students talk to other students. Therefore, in this study, researchers interacted with participants and the participants interacted with a child, but they did not interact with each other. METHODS
In this section, we describe the participants in the study, the materials and methods used to carry out the study, and the methods used to analyze the findings of the study. Participants
The participants were drawn from a pool of 94 fourth-year elementary education majors enrolled in the first of two reading methods courses at a large, state-supported university in the southeastern United States. The second reading methods course was held in conjunction with students’ preservice teaching experience. Hence, the course we chose was their last fully inclass experience before practice teaching. Close to 95% of the subject pool was made up of white, middle class females between the ages of 19 and 25 who lived in small towns and cities within the state. Participants reported taking as few as two and as many as seven science courses throughout high school and college. Approximately 72% reported having taken a physical science course, and they had taken a science methods course including physics as part of their teacher education program. Of the 94 participants, four were dropped at the beginning of the study when a pretest failed to reveal nonscientific conceptions about projectile motion and 17 chose not to be part of the study. Seventy-three teachers, then, actually participated. The Conditions
We taught principles of projectile motion while manipulating two conditions. The first was a demonstration – text condition. Teachers either participated in a demonstration before reading or merely read a text. The demonstration – text condition was created to bring about dissatisfaction with one’s current conception by asking participants to make a prediction about the outcome of a demonstration, view and explain the demonstration, and then read. The second condition was a usefulness condition. In this condition, participants were either told or not told that they were to teach a lesson to a student about the information they were learning. Demonstration. Our demonstration technique was in line with science educators’ notions
that there must be some cognitive conflict before nonscientific conceptions can be changed. We demonstrated the physics principle in a way meant to cause cognitive conflict. We asked participants to predict where an object carried at shoulder-height would fall if dropped. Because of the pretest they had taken and previous research findings (e.g., McCloskey, 1983), we were confident that most preservice teachers would predict that the object would fall straight down or backwards. Then, using a piece of tape on the floor as a reference point, we demonstrated that a carried object falls in front of the release point. We asked the teachers if their predictions were correct and, if not, to explain what really happened, encouraging them to describe the simultaneous effects of vertical and horizontal motion through a type of scaffolding. We also asked them to predict the path of cargo dropped from a moving airplane; then we
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showed a film that depicted the cargo falling forward in a curved path. Finally, we had participants make predictions about the path of a penny being shoved off a table and a bullet being fired from a gun. After each demonstration, we had them explain why the demonstration proceeded as it did, helping them to emphasize the effects of forward motion and gravity. In this demonstration procedure, other students were not involved. As previously mentioned, other research indicated that students who talk to other students often learn or solidify nonscientific information rather than scientific, and we wished to limit that influence. However, the social-constructionist nature of learning is important. Therefore, we used Leontev’s (1981) notion of appropriation. That is, the researcher appropriated students’ comments to provide them with the scaffolding needed to reason through the demonstration explanation. For example, if a preservice teacher described the path as an arc, the researcher would ask what was responsible for the arced path. If the preservice teacher could not answer, the researcher would ask what was making the object move toward the ground. (Preservice teachers could all describe the effects of gravity.) Then the researcher would ask what was making the object move forward. These and other questions helped preservice teachers appropriate scientific explanations. The scaffolding that was provided may have also served to help the preservice teachers understand the plausibility of scientific explanations. Although the demonstration procedure took only 15 – 20 minutes, it involved the teachers in rather complex processing of the targeted principle and had the potential to induce cognitive conflict. It also involved participants in using the demonstration procedure often recommended by science educators (Anderson & Smith, 1987; Champagne et al., 1983). Guzzetti et al.’s (1993) meta-analysis of science studies in conceptual change revealed that approaches including demonstration appeared to be helpful, possibly because they produced dissatisfaction with previous predictions, meeting Posner et al.’s (1982) first condition for conceptual change. Therefore, demonstration should help students learn from reading about a counterintuitive scientific principle. Usefulness. The other variable, usefulness, was chosen in deference to Posner et al.’s (1982) idea that, for conceptual change to occur, the new concept must appear fruitful (help them explain future scenarios, solve future problems) and because of our findings that students who find physics useful (relevant to their lives) are more likely to undergo conceptual change (Hynd et al., 1994). Half of the preservice teachers read a statement indicating that they should pay close attention to the information to be learned from the demonstration and/or reading because they would be teaching it to an elementary school student. A time was scheduled to teach an elementary school student for eight of the students who were told they would have that experience. We also scheduled a time for eight preservice teachers who were not told they would teach an elementary school child. We were interested in documenting differences in their lessons and their understanding of the targeted physics principles that were due to their being told or not told of the experience. Reading. A 606-word expository passage that had been adapted from an article in Scientific
American (McCloskey, 1983), titled “Newton’s Theory of Motion,” was given to all students. The adaptation had been checked for accuracy by a professor of physics at the university where the study was conducted. The passage was considered refutational, in that it contradicted the commonly held theory of impetus, a pre-newtonian explanation of projectile motion asserting that objects had internal forces which dissipated over time. The text was designed to elicit cognitive conflict, make the concept understandable and plausible, and to show its usefulness. Other students who have read the text have been asked for their com-
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ments about it (Hynd & Guzzetti, in press). They say that it is effective because it engaged their prior knowledge (they found that impetus theory was what they believed in), told them they had been inaccurate, and helped them to realize that others had also had the same nonscientific conceptions about motion. It also gave them concrete examples to explain the new theory in a way that they could understand from their daily lives. Therefore, we consider the text to be understandable and plausible and to offer a fruitful theory — one that could be used by its readers to explain the phenomena they came into contact with on a daily basis. It was calculated to be at the tenth grade readability level according to the Fry readability formula (Fry, 1977). Refutational text has previously been found to exert a positive influence on conceptual change even if not combined with other variables. Guzzetti et al. (1993) discovered that all forms of refutational text, when considered together, were superior, producing learning of counterintuitive concepts to all kinds of nonrefutational text across grade levels. Three pretests were used to measure participants’ prior knowledge about projectile motion. The first, a test of relatedness, was adapted from materials validated by Valencia et al. (1987). It assessed participants’ ability to distinguish between vocabulary terms that were either related or not related to the concept of motion. “Gravity,” “growth,” and “velocity” were three of the ten terms on the test of relatedness. A second pretest was a shortened version (n 5 10 items) of an experimenter-constructed 21-item true/false test (test/retest reliability coefficient 5 0.71). A true item reflected Newton’s theory; a false item reflected impetus theory. A third pretest, an application task, required the preservice teachers to study a diagram of a projectile shot from a cannon. Participants had to label the path the projectile would take and explain the reason for their choice of paths. These tests had been used in other studies (e.g., Hynd & Alvermann, 1989; Hynd et al., 1994). Two of three posttests were administered immediately after the treatment and, then, again after a 2-month delay. The first of these was the 21-item true/false test from which the tenitem pretest was derived. The second was the application task described earlier. The third posttest, an eight-item short-answer test, was administered only one time, immediately after the treatment. Examples of items from the short-answer test include the following: Test Materials.
1.
A person is walking forward at a brisk pace carrying a stone at shoulder height. Explain, according to Newton’s theory, where the stone would fall in relation to the point where it was dropped. 2. Why would this happen?
All of the aforementioned items — the text and the tests — had been used in other studies. Anyone desiring copies of these instruments may write to the first author and receive copies of them. Questionnaire. We investigated preservice teachers’ attitudes and their formal and informal
learning experiences in science. Preservice teachers completed a 16-item questionnaire designed to elicit responses to questions regarding: (a) the number of science courses taken; (b) beliefs about the importance of science, in general, and physics, in particular; (c) ratings of their own knowledge; and (d) attitudes toward and experiences with teachers, textbooks, demonstrations, formal instruction, and informal learning experiences. Preservice teachers were directed to rate issues such as importance and attitudes on a five-point Likert scale, but were also asked to write explanations for each item rated. This questionnaire was evaluated informally (as we would an interview), using descriptive techniques that assessed the
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responses to individual rather than pooled questions. In addition, the 16 items were meant to tap separate areas of influence, so we believed the correlation between items to be of little importance. Because of this, reliability is not reported. However, the questionnaire had a great deal of construct validity. Note our earlier discussion of the importance of affective feelings about physics as a topic. We believed that many preservice teachers would think that physics was important, but would not be able to define why it would be useful to them personally. Indeed, another study has pointed to the idea that usefulness is an important variable to consider apart from perceived motivation to learn physics, which could be due to extrinsic factors such as getting a good grade or getting the approval of peers (e.g., Hynd et al., 1994). We also believed that past experiences with instruction is a determining factor in students’ attitudes toward instruction in physics. In the study cited earlier, for example, we found that positive attitudes about the structure of the classroom and the topics covered in physics accounted for a significant amount of variance in postlesson achievement tests about counterintuitive physics concepts. Finally, we were struck with students’ attitudes toward physics text in our previous studies. Generally, attitudes toward text (in most cases, physics textbooks) are negative. Yet, researchers have found consistently positive results from reading refutational text (Guzzetti et al., 1993). For these reasons, the questionnaire tapped what we believed were important constructs. Videotaped Teaching and Postteaching Interview. In order to have qualitative documentation of preservice teachers’ ideas about Newtonian principles after instruction, 16 preservice teachers were videotaped as they taught concepts of motion to a fifth grade child. We also designed a ten-item structured, audio-recorded, postsession interview in which participants were asked to rate and explain their level of knowledge, comfort in teaching, and success in teaching the targeted physics principle.
Procedure
The study was conducted in four phases. In phase 1, the test of relatedness, the ten-item true – false test, and the application task were used as pretests to determine preservice teachers’ levels of prior knowledge about Newton’s first law of motion, their ability to apply the law, and their nonscientific conceptions about it. Only those who held nonscientific notions were retained in the study. Teachers were considered to have nonscientific notions if they chose the wrong path of the projectile in the application pretest and/or gave the wrong explanation for the projectile’s path. If the correct path were chosen, and a borderline explanation given, key items reflecting general principles were checked on the multiple-choice test. In phase 2, the preservice teachers were assigned to one of four groups representing the two levels of demonstration (Demo – Text/Text only) and two levels of usefulness (Told/Not Told). Participants were required to attend a one-on-one (researcher and participant) session that lasted between 50 and 60 minutes. In the Demo – Text/Told condition, preservice teachers were told (in writing) about the forthcoming videotaped lesson they would teach an elementary school child as they entered the session. Next, they participated in several demonstrations of Newton’s first law of motion in which they made predictions and then compared those predictions to the outcomes of the demonstrations. They also read the one-page refutational text on Newton’s theory of motion, worked on a buffer activity to control for the effects of short-term memory, and completed a short-answer test, a 21-item true/false test, and an application task. Except for not being told about the videotaped lesson that would follow in phase three, those in the
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Demo – Text/Not Told group participated in the same activities as those in the Demo – Text/Told group. Participants in the Text only/Told and Text only/ Not Told groups worked on word search puzzles that contained words taken from the stimulus passage in lieu of the demonstrations. They, like the other two groups, then read the stimulus passage and completed the posttests. Finally, all preservice teachers were given the attitude questionnaire to complete after the session. In phase 3, eight randomly selected participants who had been told they would use their newly acquired information in an actual lesson and eight who had not been told were videotaped as they individually taught a fifth grade student. Four teachers in the Told and four in the Not Told group had been exposed to the Demo – Text condition. As the participants entered the room where they would teach, they were provided with a set of materials that they could use if they liked, but they were not given time immediately before the lesson to prepare. We placed this constraint of no preparation time on the preservice teachers because we wanted to reduce the possibility that some teachers would prepare elaborate lessons reflecting nontreatment information rather than information recalled from the treatment. Participants were reassured that no one else was allowed to prepare and that their level of preparation would not be judged. They were also told that they could have as much time as they wished to explain the concept. Audiotaped interviews were held with each of the 16 preservice teachers following their lessons. In phase 4, approximately 2 months after the initial lesson, the true/false test and the application task administered in phase 2 were readministered as delayed posttests. Only two tests were given because of time constraints. Scoring and Interpreting Data Pre- and Posttests. We scored each of the pretests and posttests without knowledge of the group membership of the preservice teachers. Scores on all measures except the short-answer test, the application task, and the questionnaire were obtained by comparing participants’ responses to the responses on a prepared answer key. On the six-item, short-answer test, we awarded one point to each correctly answered question except for questions 2 and 4, which were two-part answers and awarded one point for each part. The application task scores ranged from zero to two. Full credit was awarded if participants correctly labeled the path the projectile would take and gave the correct explanation for their choice of paths. One point was awarded if participants either correctly labeled or explained the path the projectile would take. Zero points were awarded for a completely nonscientific answer.
Preservice teachers’ beliefs about the importance of science in general and physics in particular, their knowledge level, their attitudes, and their feelings about the influence of teachers, text, formal instruction, and informal experiences were tabulated using data from the 16-item questionnaire. In the case where rating scales were not used (on items about teachers, text, formal instruction, and informal experiences), each written answer to a question was rated as negative, neutral, or positive and assigned a score of 1, 2, or 3, respectively. In addition, the 16 videotaped teachers’ questionnaires were separated from the other questionnaires and the explanations that the participants supplied were analyzed qualitatively.
Questionnaire.
Videotaped Lessons. Two researchers viewed, transcribed, and coded the 16 videotaped
lessons and the postteaching interviews, looking for evidence of an overall correct explanation
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of the physics principle that had been taught, noting the length of the lesson, and noting the self and fifth graders’ ratings of the teacher. The data are shown in Table 4. Another researcher viewed each of the videotapes and read the transcriptions in order to discover patterns not previously identified. She noted that the teachers often appeared to hold seemingly contradictory ideas. With that observation in mind, she then analyzed the demonstrations, the text, and all test items for discrete concepts of motion, concepts that could be held independent of others. Four concepts were identified. The first was the idea that a horizontally propelled projectile’s path will form an arc on its way to the ground. The second was that something that is carried (in motion) and released will maintain its forward motion. The third idea was that horizontal motion and gravity are both independent influences in the path of a projectile, thus explaining why the object moves in an arc rather than first going out and then down. The last idea was that forces are external to the projectile: that is, changes in motion are brought about by external forces rather than internal ones. All of these ideas were introduced in both the demonstration and in the text and were tested as well. Once these discrete concepts were identified, all data records of the 16 videotaped students (pretests, posttests, videotaped lesson, structured interview, and delayed posttests) were coded for evidence that preservice teachers either had or lacked these concepts. In the case of the true – false and other forced-choice items, only a lack of the concept could be documented, because a preservice teacher could choose a scientific answer by chance. In the open-ended questions, the videotaped lessons, and the interviews, both scientific and nonscientific principles could be noted, if mentioned. In this way, we could trace an identified nonscientific conception from pre- to posttest to delayed posttest. The contents of the videotaped lesson and interviews provided informal opportunities to view preservice teachers’ thinking about the targeted concepts and to note if (and sometimes why) these concepts changed during the course of the study. To interpret the data, we arranged the coded items on a matrix for each teacher (Miles & Hubermann, 1984) and included scores from the pre- and posttests. From these individual matrices, we analyzed: (a) how many categories of nonscientific concepts were held by teachers at the start and end of the study; (b) which nonscientific concepts were more prevalent; (c) which nonscientific concepts seemed to be replaced by scientific ones; and (d) what behaviors seemed to explain changes either from nonscientific to scientific thinking or visa versa. The Appendix shows examples of these matrices. Finally, all the data on two of the preservice teachers who were videotaped were analyzed qualitatively. We attempted to describe the interaction of variables that resulted in conceptual change at the end of the study. RESULTS AND DISCUSSION
In this section, we present quantitative findings and discussion, then the descriptive and qualitative observations and discussions. In a subsequent section, we discuss, in a general way, the cumulative findings of the entire study. Quantitative Analysis
The quantitative parts of our study were undertaken to help us answer the first two questions we posed earlier: (a) Will combining demonstration and reading enable preservice teachers to overcome their prior conceptions? (b) Will telling preservice teachers that they will be expected to teach a concept provide the necessary motivation for overcoming prior conceptions? To see if possible group differences existed prior to instruction, three one-way analyses of variance were run on each of the pretests. None of the groups differed significantly on any of the tests. The posttests were then analyzed using either analysis of covariance or analysis of
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covariance with repeated measures. A 2 (Demo – Text/Text only) 3 2 (Told, Not Told) completely crossed design was used. The relatedness pretest, which resulted in the greatest reduction of error variance, was the covariate for all posttests. An analysis of covariance was run on the 73 observations obtained for the short-answer posttest. Separate analyses of covariance with repeated measures were conducted for the immediate and delayed true/false and immediate and delayed application task posttests. Absenteeism at the time of the delayed tests resulted in dropping 6 of the 73 subjects from the analyses. Consequently, immediate and delayed posttest measures for the true/false and application tasks were analyzed using data from 67 subjects. Tables 1, 2, and 3 present the adjusted means and standard deviations by group for each of the posttests. Short-Answer Posttest. The analysis of covariance on the short-answer posttest revealed a statistically significant main effect for Demo – Text, F(1,68) 5 7.34, p 5 0.01, in favor of the group that participated in the prediction/Demo – Text, but not for Told, F(1,68) 5 0.68, p 5 0.42. No statistically significant interaction was found between Told and Demo – Text, F(1,68) 5 2.80, p 5 0.10. Effect sizes were calculated by expressing mean differences between the Demo – Text and Text only groups in standard deviation units (see Glass et al., 1981). On the main effect for Demo – Text, R2 5 0.14, with an effect size of 0.64. Immediate and Delayed True – False Posttests. The analyses of covariance with repeated measures on the true/false posttests revealed a statistically significant main effect for Demo – Text, F(1,62) 5 5.85, p 5 0.02, in favor of the group that participated in the Demo – Text, on the immediate true/false posttest, but not on the delayed true/false posttest, F(1,62) 5 0.43, p 5 0.52. There were no statistically significant main effects for Told on either the immediate, F(1,62) 5 1.11, p 5 0.30, or the delayed, F(1,62) 5 0.79, p 5 0.38, true/false posttests. On the main effect for Demo – Text, R2 5 0.11, with an effect size of 0.48. There was no statistically significant interaction between Told and Demo – Text on either the immediate, F(1,62) 5 0.41, p 5 0.53, or delayed, F(1,62) 5 0.67, p 5 0.42, true/false posttests. Immediate and Delayed Application Task. The analyses of covariance on the application task revealed a statistically significant main effect for Demo – Text, F(1,62) 5 10.09, p 5 0.005, in favor of the group that participated in the Demo – Text condition on the immediate application task, but not on the delayed application task, F(1,62) 5 1.87, p 5 0.18. There were no statistically significant main effects for Told on either the immediate, F(1,62) 5 0.25, p 5 0.62, or the delayed, F(1,62) 5 0.00, p 5 0.99, application tasks. On the main effect for
TABLE 1 Adjusted Means (M ) and Standard Deviations (SD ) by Group on Short-Answer Posttest Group
Number
M
(SD)
Demonstration No Demonstration Told Not Told
39 34 36 37
6.65 5.76 6.07 6.34
(1.38) (1.39) (1.37) (1.53)
Highest possible score 5 8.
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TABLE 2 Adjusted Means (M ) and Standard Deviations (SD ) by Group on Immediate and Delayed True/False Posttests Immediate
Delayed
Group
Number*
M
(SD)
M
(SD)
Demonstration No Demonstration Told Not Told
33 34 34 33
18.56 17.48 17.78 18.27
(1.74) (2.26) (2.33) (1.78)
16.78 16.39 16.32 16.85
(2.56) (2.32) (2.65) (2.20)
*In repeated measures analysis, observations with missing values are not used.
Demo – Text, R2 5 0.18, with an effect size of 0.70. There was no statistically significant interaction between Told and Demo – Text on either the immediate, F(1,62) 5 1.07, p 5 0.31, or the delayed, F(1,62) 5 0.79, p 5 0.38, application tasks. As mentioned, the quantitative part of the study was initiated to answer the first two questions. These are discussed next. Will Combining Demonstration and Reading Enable Preservice Teachers to Overcome Their Prior Conceptions? Preservice teachers who made predictions and saw demonstra-
tions before reading a text did significantly better than the read-only groups on all three of the immediate outcome measures. This finding supports Marshall’s (1989) study of preservice elementary teachers. In that study, the combination of demonstration and reading produced the greatest change in subjects’ understanding of the causes of seasonal change. After 2 months had elapsed, however, it was impossible to distinguish between participants in the Demo – Text and Text only groups, at least as measured by their performances on the delayed true – false and application tasks. The lack of posttest differences after 2 months does not mean, however, that participants maintained their nonscientific ideas in the long term. In a post hoc 2 (Demo – Text/Text only) 3 2 (posttest/delayed posttest) split-plot ANOVA (the Demo – Text and Text only groups were contrasts of different individuals and the posttest — delayed posttests were contrasts of the same individuals), where test consisted of application pretest and application delayed posttest, we found that although the effects of Demo – Text
TABLE 3 Adjusted Means (M ) and Standard Deviations (SD ) by Group on Immediate and Delayed Application Posttests Immediate
Delayed
Group
Number*
M
(SD)
M
(SD)
Demonstration No Demonstration Told Not Told
33 34 34 33
1.70 1.17 1.48 1.39
(0.57) (0.76) (0.74) (0.69)
1.58 1.38 1.48 1.48
(0.56) (0.70) (0.66) (0.62)
*In repeated measures analysis, observations with missing values are not used.
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were nonsignificant, there were significant differences between pretest and delayed posttest scores, F(1,65) 5 109.75, p 5 ,0.001, on the application task. Therefore, preservice teachers did change their previous ideas about motion, regardless of whether they were in the Demo – Text or Text only group. Furthermore, there was no significant loss of concepts for either the Demo – Text or Text only groups on the true – false delayed posttest when compared to the immediate posttest, (Fs,2). This finding supports our other research with high school students, which suggested that reading produced long-term gains while demonstration did not (Hynd et al., 1994). Our interpretation of these results is that some long-term conceptual change occurred. Because the only factor experienced by all groups was the text, we speculate that the text, rather than the demonstration, may have helped solidify concepts. The effect of demonstration lessened over time. The long-term benefits of text versus demonstration should be the focus of subsequent research. Will Telling Preservice Teachers That They Will Be Expected to Teach a Concept Provide the Necessary Motivation for Overcoming Prior Conceptions? In our study,
attempting to manipulate the usefulness of the information to be learned had no effect on subsequent conceptual change. We had anticipated that giving elementary education majors advance information of an impending teaching assignment would increase motivation to learn the physics principle. That it did not produce the desired effect might be explained in several ways. Perhaps telling preservice elementary teachers they would have to teach the physics principle produced anxiety, counteracting any potential increase in motivation. Perhaps the teachers did not believe they would really be called on to teach a physics principle to an elementary school student. Another possibility, however, is that the participants in both the Told and Not Told groups were already motivated, and any attempt to increase motivation by making the information useful was superfluous. They may have been at least extrinsically motivated to achieve under any circumstance, and increasing a topic’s usefulness, in the sense of merely being able to explain a concept, may have had little bearing on their motivation. It seems plausible to assume that these teachers-in-training were conditioned to want to do well on tests and to present a good “face” when explaining the concepts to a child while being videotaped. But it was Posner et al.’s (1982) original idea that usefulness implied the ability to help one solve future problems rather than the ability to explain information. In addition, teachers-in-training may not have the sense of urgency to learn physics that engineers-intraining have, explaining why this usefulness condition did not appear to be as good at explaining the participants’ behavior as that in a previous study where high school honors physics students (who were, by and large, planning on careers that used physics) found learning physics useful (Hynd et al., 1994). Teachers merely have to teach physical principles. Engineers must rely on them for their livelihood. And individuals become elementary school teachers because of their love of children or perhaps their love of other subjects rather than their love of physics. But individuals do not become engineers or engage in other physicsrelated careers unless they love physics. Therefore, our usefulness condition may have been inadequate to test the notion we proposed to test. In the other research, cited previously, we found that usefulness appeared to be an important variable in determining whether students underwent conceptual change about physics topics. Students who believed that physics was relevant to their lives in either a substantive or aesthetic way (i.e., need it for career, want to appreciate physics in daily life) were more interested in truly understanding counterintuitive scientific explanations of ideas. Teachers-in-training may not feel that physics is especially relevant to their lives. That would be unfortunate, because their teaching of physical principles would be enhanced by a sense of relevance.
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Descriptive/Qualitative Analysis Analysis of Questionnaire. From the questionnaire we found that:
1.
2.
3.
4.
5. 6.
Participants’ attitudes about science were somewhat neutral when the field was considered as a whole (M 5 5.38 on a ten-point scale). When other science courses and physics were separated, however, participants reported liking the other sciences more than physics (M for physics 5 3.6). Most participants felt uncomfortable with their knowledge about the sciences in general and physics in particular. When other sciences and physics were considered together, students rated their knowledge as being somewhat low (M 5 4.28 on a ten-point scale). They rated their knowledge of physics lower still (M 5 2.2). Generally, participants felt that science was important to study (M 5 7.14 on a tenpoint scale). This was also true of physics. They rated the importance of physics just as high (M 5 7.15) as the other sciences. While participant ratings were high, however, their comments revealed less enthusiasm. While only one person made negative comments about the importance of science, there were eight such comments about the irrelevance of physics. The preservice teachers disliked science textbooks. The mean rating on a three-point scale was 1.67, with a one being negative, two being neutral, and three being positive. They thought science textbooks were boring, hard to understand, irrelevant, and unnecessary. The teachers liked demonstrations and experiments. The mean rating on a three-point scale was 2.82. Most of the participants had neutral to negative formal experiences in science classes. The mean rating on a three-point scale was 1.57. Students cited the teacher, the text, and the assignments for their negative feelings.
We contrasted the delayed posttest results of those who rated themselves high or low in knowledge, attitude, importance, and usefulness. These data are presented in Table 4. In every case except importance, those who rated themselves higher did better on the delayed multiplechoice and application test than those who rated themselves lower. What Influences Do Prior Experiences and Attitudes Have on Conceptual Change From Reading? Many preservice teachers had endured negative experiences with
physics and disliked science texts, preferring demonstrations. Despite these negative feelings, however, they still felt that science, including physics, was important to learn. This
TABLE 4 Means of Delayed Multiple-Choice and Application Tests for High and Low Rating of Knowledge, Attitude, Importance, and Usefulness Knowledge
Multiple-choice Application N
Attitude
Importance
Usefulness
51
; inner force (launched) •.
Symbols: > forward motion; 5 simultaneity; • inner force.
Two forces, forward motion and gravity cause things to move to earth 5
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Examples of Matrices for Subject D. L. Condition #: 15 (Demo/Told) Pretest info. and scores H.S. and college science courses True/false test Application
Post-demo info. and scores True/false test Application test Short-answer test Minilesson Attitude questionnaire
Video lesson info. and scores Knowledge Teaching Student rating Interview
Delayed posttest info. and scores True/false Application
Nonscientific Conceptions
6 5/10 1/2
18/21 2/2 8/8 6/10 Knowledge 3; attitude 8; importance 7.7; usefulness 1
Lack of forward motion (carried, tossed) >; arced path X; simultaneity 5.
Idea of two forces (launched).
Lack of forward motion > (tossed); arced path (launched) X.
Simultaneous external force (launched, carried) 5 •.
6/10 8/10 8/10
19/21 2/2
Scientific Conceptions
Simultaneous combination of two forces 5 External forces act like pressure • (treatment caused her to realize previous ideas were wrong). Lack of forward motion > (tossed)
Simultaneous combination of two forces 5
Symbols: X Arced path; > forward motion; 5 simultaneity; • inner force.
REFERENCES Alvermann, D. E., & Hynd, C. R. (1989). Effects of prior knowledge activation modes and text structure on nonscience majors’ comprehension of physics. Journal of Educational Research, 83, 97 – 102. Anderson, C. W., & Smith, E. L. (1987). Teaching science. In V. Richardson-Koehler (Ed.), Educators’ handbook: A research perspective New York: Longman, pp. 84 – 111. Carey, S., & Smith, C. (1993). On understanding the nature of scientific knowledge. Educational Psychologist, 28, 235 – 251. Champagne, A. B., Gunstone, R. F., & Klopfer, L. E. (1983). Naive knowledge and science learning. Research in Science & Technological Education, 1, 173, 183. Chinn, C. A., & Brewer, W. F. (1993). The role of anomalous data in knowledge acquisition: A theoretical framework and implications for science instruction. Review of Educational Research, 63, 1 – 49.
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Duit, R. (1991). On the role of analogies and metaphors in learning science. Science Education, 75, 649 – 672. Fry, E. (1977). Fry’s readability graph: Clarifications, validity, and extension to level 17. Journal of Reading, 21, 242 – 252. Gilovich, T. (1991). How we know what isn’t so: The fallibility of human reason in everyday life. New York: The Free Press. Glass, G. V., McGraw, B., & Smith, M. L. (1981). Meta-analysis in social research. Beverly Hills, CA: Sage. Guzzetti, B. J., Snyder, T. E., Glass, G. V., & Gamas, W. S. (1993). Meta-analysis of instructional interventions from reading education and science education to promote conceptual change in science. Reading Research Quarterly, 28, 116 – 161. Hewson, P. W., & Hewson, M. G. (1984). The role of conceptual conflict in conceptual change and the design of science instruction. Instructional Science, 13, 1 – 13. Hynd, C. R., & Alvermann, D. E. (1989). Overcoming misconceptions in science: An on-line study of prior knowledge activation. Reading Research and Instruction, 28, 12 – 26. Hynd, C. R., & Guzzetti, B. (in press). Teachers, text, and culture: The influence of context on students’ conceptual change in science. Project funded by the National Reading Research Center, University of Georgia, Athens, GA. Hynd, C., McWhorter, Y., Phares, V., & Suttles, W. (1994). Instructional variables in conceptual change in high school physics classes. Journal of Research in Science Teaching, 31, 933 – 946. Hynd, C. McNish, M., Qian, G., Keith, M., & Lay, K. (1994). Learning counterintuitive physics principles: The effect of text and educational environment. Technical report to the National Reading Research Center, Athens, GA. Lederman, N. G., & Gess-Newsome, J. (1991, April). Subject matter structures: Abstractions confront the world of teaching. Paper presented at the annual meeting of the American Educational Research Association, Chicago, IL. Kuhn, D., Amsel, E., & O’Loughlin, M. (1988). The development of scientific thinking skills. Orlando, FL: Academic Press. Lee, O. (1991, April). Motivation to learn subject matter content: The case of science. Paper presented at the annual meeting of the American Educational Research Association, Chicago, IL. Lloyd, C. V. (1990, December). The enactment of literacy in high school biology classrooms: Two case studies. Paper presented at the annual meeting of the National Reading Conference, Miami, FL (ERIC Document Reproduction Service No. ED 337747). Leontev, A. N. (1981). Problems of the development of mind. Moscow: Progress Publishers. Maria, K., & MacGinitie, W. (1981, December). Prior knowledge as a handicapping condition. Paper presented at the annual meeting of the National Reading Conference, Dallas, TX. Marshall, N. (1989). Overcoming problems with incorrect prior knowledge: An instructional study. In J. Zutell & S. McCormick (Eds.), Cognitive and social perspectives for literacy research and instruction, 38th yearbook of the National Reading Conference. Chicago, IL: National Reading Conference, pp. 323 – 330. McCloskey, M. (1983). Intuitive physics. Scientific American, 248, 122 – 130. Miles, M. B., & Hubermann, A. M. (1984). Qualitative data analysis: Sourcebook of new methods. Beverly Hills, CA: Sage. Newport, J. F. (1990). Elementary science texts: What’s wrong with them? Education Digest, 56, 68 – 69. Osborne, J. H., Jones, B. F., & Stein, M. (1985). The case for improving textbooks. Educational leadership, 42, 9 – 16. Pintrich, P. R., Marx, R. W., & Boyle, R. (1993). Beyond cold conceptual change: The role of motivational beliefs and classroom contextual factors in the process of conceptual change, Review of Educational Research, 63, 167 – 199. Pratt, H. (1981). Science education in elementary school In N. C. Harms & R. E. Yager (Eds), What research says to the science teacher. Vol. 3. Washington, DC: National Science Teachers Association, pp. 73 – 94.
PRESERVICE TEACHERS
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Posner, G. J., Strike, K. A., Hewson, P. W., & Gertzog, W. A. (1982). Accommodation of a scientific conception: Toward a theory of conceptual change. Science Education, 66, 211 – 227. Schibeci, R. A. (1989). Home, school, and peer group influences on student attitudes and achievement in science. Science Education, 73, 13 – 24. Schommer, M. (1990). Effects of beliefs about the nature of knowledge on comprehension. Journal of Educational Psychology, 82, 498 – 504. Schymansky, J. A., Yore, L. D., & Good, D. W. (1991). Elementary school teachers’ beliefs about and perceptions of elementary school science, science reading, science textbooks, and supportive instructional factors. Journal of Research in Science Teaching, 28, 437 – 454. Songer, N. B., & Linn, M. C. (in press). How do students’ view of science influence knowledge integration? Journal of Research in Science Teaching, 28. Strike, K. A., & Posner, G. J. (1990). A revisionist theory of conceptual change. In R. Duschl & R. Hamilton (Eds.), Philosophy of science, cognitive science, and educational theory and practice. Albany, NY: SUNY Press. Talton E., & Simpson, R. (1987). Relationships of attitude toward classroom environment with attitude toward and achievement in science among tenth grade biology students. Journal of Research in Science Teaching, 24, 507 – 525. Valencia, S., Stallman, A. C., Commeyras, M., & Greer, E. (1987, December). Three methods of assessing prior knowledge: A validation study. Paper presented at the annual meeting of the National Reading Conference, St. Petersburg Beach, FL. Yore, L. D. (1991). Secondary science teachers’ attitudes toward and beliefs about science reading and science textbooks. Journal of Research in Science Teaching, 28, 55 – 72.
