Animation of the Solution Process of Table Salt - Springer Link

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Journal of Science Education and Technology, Vol. 10, No. 1, 2001

A Hypermedia Environment to Explore and Negotiate Students’ Conceptions: Animation of the Solution Process of Table Salt Jazlin V. Ebenezer1

This article describes the characteristics and values of hypermedia for learning chemistry. It reports how a hypermedia environment was used to explore a group of 11th grade chemistry students’ conceptions of table salt dissolving in water. It then presents how the hypermedia was used by students to negotiate meaning for two conceptualizations about the process of dissolving table salt in water: (a) the transformation of solid to liquid, and (b) the chemical combination of solute and solvent. This article traces the nature of students’ conceptions for the solution process of table salt. The findings of this study indicate that a hypermedia environment can be used to explore, negotiate, and assess students’ conceptions of the submicroscopic aspects of solution chemistry. Further, this article discusses the successes and difficulties pertaining to the learning of solution chemistry in a hypermedia environment, and presents an account of an improved version for future study. KEY WORDS: Student conceptions; phenomenography; descriptive categories; hypermedia animation; dissolving; submicroscopic ideas.

INTRODUCTION: CHILDREN HAVE DIFFICULTIES LEARNING ABOUT CHEMICAL PROCESSES

Treagust, 1992a, 1992b; Lijnse et al., 1990; Novick and Nussbaum, 1978; Renstr ´ om, ´ 1988). Three earlier studies show evidence that children have difficulties learning about dissolving. Cosgrove and Osborne (1981) interviewed secondary students in New Zealand to find students’ conceptions of the solution process. These students were shown a teaspoon of sugar dissolving in water and were asked, “What happens to the sugar?” These researchers reported that over 25% used the words “melt” and “dissolve” synonymously. Abraham et al. (1994) found that out of a sample of 100 students from junior high, high school, and college chemistry some understanding of the concept of dissolution was held by 60.7% of the students, with 27.3% of the responses indicating sound understanding. Sound understanding responses were those that included the ideas that as a sugar cube dissolves, the cube breaks up and evenly mixes with the water at a molecular level. Partial understanding responses contained either the break up of the cube structure or the homogeneous mixing of

The understanding of chemical processes such as melting, evaporating, dissolving, diffusion, electron transfer, ion conduction, and intermolecular bonding is fundamental to learning high school chemistry. Chemists use particle models to account for these abstract constructs. However, students find it difficult to visualize chemists’ conceptual models (Abraham et al., 1994; Bar and Galili, 1994; Bar and Travis, 1991; Ben-Zvi et al., 1986; Brook et al., 1984; Butts and Smith, 1987; Cosgrove and Osborne, 1981; Ebenezer and Erickson, 1996; Gabel et al., 1987; Garnett and

1 Department

of Curriculum, Teaching and Learning, Faculty of Education, The University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada. e-mail: [email protected]

73 C 2001 Plenum Publishing Corporation 1059-0145/01/0300-0073$19.50/0 °

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74 the sugar and water. Partial understanding was also given if the response included both parts required for sound understanding, but the drawing showed uneven mixing. Ebenezer and Erickson (1996) identified a number of conceptions of solubility elicited from 11th grade students in individual interviews. Students’ preferred explanations for solubility phenomena more specifically related to the present study are the physical transformation from solid to liquid, and the chemical transformation of solute. It was argued that the newly acquired conceptions of solubility as a result of instruction reflected insufficient explanatory power and were merely overlaid with the chemical language. Learning the language of solution chemistry was reflected in the change between pre- and postinstructional conceptions. The foregoing studies suggest that students find it difficult to link submicroscopic explanations of chemical systems to their macroscopic observations as well as to work in both these levels simultaneously and comfortably. Hence, appropriate teaching strategies must be identified and assessed in the context of chemistry classrooms to help students construct a deeper understanding of the chemical concepts.

HYPERMEDIA MIGHT HELP Students’ difficulties with the understanding of the particulate nature of matter prompted me to survey the literature on the application of computers within a constructivist framework and, more importantly, how the application of computer animations can accommodate students’ conception of chemical processes in teaching chemistry units. The science education literature suggests that pictorial representations of atomic and molecular models provide opportunities for students to better understand chemical concepts (Alesandrini and Rigney, 1981; Gabel, 1993; Mcintosh, 1986; Noh and Scharmann, 1997). Depicting chemical processes using advanced computer capabilities and software is not out of reach for present day teachers and students. Jonassen (1996) states that hypermedia “nodes” that include text, graphic images, a sound byte, and animation sequences or video clips offer rich sensory experiences for the learners. Studies on computeraided instruction, in fact, indicate teachers’ desire to use a chemistry module on polymer because of its three-dimensional, animated molecular models that explain polymerization and stretching processes (Dori and Barnea, 1997). In addition, computer mod-

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Ebenezer els allow students to link their submicroscopic explanations of chemical systems with their macroscopic observations. When students can visualize submicroscopic processes in chemistry they are better able to construct a meaningful understanding of chemical knowledge (White, 1988) such as “strings” (symbols and equations), “propositions” (relationships among concepts), and “logicomathematical understanding” (mathematical problem solving—e.g., working out solution concentration problems). Hence, appropriate teaching strategies that incorporate computer technology can advance chemistry courses.

Hypermedia and Its Value in Chemistry Learning Because of its capability to animate chemical processes I have found that hypermedia serves as a valuable teaching tool in chemistry education. The primary feature of the hypermedia environment is the combination of multimedia and hypertext (Jonassen, 1996). Twentieth-century multimedia is computer based and integrates “text, graphics, animation, video, imaging, and spatial modeling” (von Wodtke, 1993 as cited in Jonassen, 1996, p. 185). Hypertext is a nonlinear and nonsequential way of arranging and displaying text. The fundamental storage unit of a hypertext is the node. A node stores text; simply, a “card” containing text. Because each node consists of links to other related nodes (depending on the author’s wish and the various types of knowledge in a domain of science) a learner may access any other nodes while reading text on one node. For instance, suppose a learner is reading a description of what is meant by solubility on one node or card. The same card may be “linked” to other nodes such as (a) instructions for how to determine the solubility of salt, (b) a data chart to record solubility results, (c) a graph sheet on which a graph is drawn, and (d) solubility problems. Hence, while a student has one node open she can also access other nodes through transparent or hidden buttons. (These buttons or “hot links,” may be highlighted words.) This is possible because there are links and interlinks made to nodes through a scripting language that makes hypertext dynamic. In addition to text, a node in a hypermedia environment can display a particular media or a combination of appropriate media. A node therefore may consist of text, graphics, photographic images, animations, sound, and audio or video sequences. Instead of reading about the solution process, students can actually see the solution process through animations. Ionic

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equations become meaningful for students because they visualize the solution process. Hypermedia thus provides students with a visual experience of chemical processes. To develop or run multimedia programs “highresolution monitors, sound and video compression cards, and high RAM and processing speed” (Jonassen, 1996, p. 185) are required. One must learn how to capture sound and video, how to synthesize sound and video to get special effects, how to import graphics or draw free hand, and how to combine the desired graphics by using “scripts”—a language that the computer can understand—to produce animation. In my most recent multimedia presentation on the process of “dissolving” (Ebenezer, 1996), I have integrated text as well as video sequence of teacher demonstrations and explanations of key concepts for solution chemistry. For example, one mulimedia episode illustrates the polarity of water through text and video clips and includes animations of the solution process. In this program students use the drawing program that is linked to the project. Students can actually draw their own visual representations of dissolving and present them to their peers, engaging in a meaningful conversation about their constructs with peers and their teacher via Internet relay chat. While ideally there is nonsequentiality to multimedia, making it possible to access information randomly, an initial chemistry lesson sequence should be progressive to allow students to see the hierarchy of knowledge. A multimedia presentation with a few hypertexts can be developed so that the learner moves sequentially through key processes. The three levels of chemical knowledge (Johnstone, 1991) in this hierarchy include “macroscopic” aspects such as table salt dissolving in water, “submicroscopic,” theoretical concepts and models like the chemical structure of sodium chloride and water (the dissolution process at the particulate level), and the “symbolic system” Eq. (1). − NaCl(s) + H2 O → Na+ (aq) + Cl(aq)

(1)

The use of few hypertexts is essential so a learner does not get disoriented with millions of hypertexts such as found on some Internet systems like Netscape. An advantage of Netscape is that students can create their own hypertexts to reveal their own personal or collective understanding. Students thus have the opportunity not only to learn from the hypertext but also to learn with the hypertext; that is, they can create their personal nodes (Salomon, Perkins, and Globerson, 1991). This process of creating interrela-

tionships helps student become more sophisticated learners rather than producers of hypertexts. Indeed, students using hypermedia programs may be asked to interconnect multiple representations of knowledge. In chemistry this would be “strings, propositions, images, and episodes.” Students would thus utilize intellectual skills, motor skills, and cognitive strategies (White, 1988). Conjunctively, according to Gardner (1991) students would access knowledge domains or critical forms of knowing including notational conventions, epistemic rules, and conceptual understandings. Students who learn how to interrelate various types of knowledge can move through a hypermedia environment choosing what they wish to study, focusing on concepts with which they are having difficulty, or creating their own research problems. The student learns at her own pace because the decision to move on or not is in the hands of the learner. A Hypermedia Environment for Depicting the Solution Process of Table Salt HyperCard is a hypermedia environment that allows people to create programs that have particular structures and functions. HyperCard has an extensive database capable of organizing text, graphics, photographic images, and audio. The HyperCard, an authoring medium, uses a programming or scripting language called “hypertalk” that enforces “buttons” to navigate from one “card” to another in the same “stack,” play audio or videoclips, animate graphics, and reveal hidden “hypertext.” Hypertext utilizes random access to information thus enabling the learner to take control of and explore knowledge in a nonlinear fashion (Marsh and Kumar, 1992). Because of the multimedia capabilities and multisensory modalities of learning, HyperCard, a thinking and negotiating environment, allows students to be active constructors rather than passive receivers of knowledge (Gabel, 1994). HyperCard was chosen as the authoring system to depict the solution process for this study. For instance, the separation and hydration of the sodium ion and the chloride ion can be graphically represented and shown through animations. In this HyperCard program, hypertext also consistuted the explanation of how hydration takes place and to write the corresponding ionic equation. Simultaneously, “teacher talk” can be played by clicking on the “sound” button to focus students’ attention on the specific details of the lesson. Although through quick time movies, a video excerpt of an expert’s ideas, discussions of the solution process may be captured, imported, and

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76 played, this was not available in this Hypermedia lesson on dissolving. By combining text, graphics (still and animations), and sound, a unique stack may be created to explore students’ conceptions as well as to incorporate those conceptions through a negotiatory process. Hypermedia for Exploring and Negotiating Students’ Conceptions Researchers such as Di Sessa (1987), Hennessy et al. (1993), Twigger et al. (1991), Twigger et al. (1994), White and Horwitz (1988), and Zietsman and Hewson (1986) have developed “computer simulations” in physics to explore and incorporate children’s ideas in science instruction. For example, a recent study (Langley et al., 1997) on students’ conceptions of light propagation and visual patterns has adovcated the use of the following computer programs: The RAY optics simulation software (Ronen et al., 1993; Ronen and Rivlin, 1995) and the Visual Physics Optics Simulation (Tek, 1994) in instructional environments. These physics education researchers and authors see the computer as providing a context in which students’ conceptions may be explored and negotiated through simulations. Chemistry education researchers have focused on computer animations for addressing students’ conceptions of chemical processes. For example, Williamson and Abraham (1995) studied the effect of computer animations depicting the particulate nature of matter on college chemistry students’ mental models of chemical phenomena such as phase transitions, intermolecular forces, solutions, ions, precipitation, and temperature effects on dissolving. These authors reported that their treatment groups received significantly higher conceptual understanding scores on a Particulate Nature of Matter Evaluation Test. Sanger and Greenbowe (1997) have identified college students’ misconceptions in electrochemistry. One of the common misconceptions was the notion that electrons flow through the salt bridge and electrolyte solutions to complete the circuit. Burke et al. (1999) suggested that using computer animations depicting chemical reactions on the molecular level and a teaching approach that confronted student misconceptions dramatically decreased the proportions of students consistently demonstrating the misconception that electrons can travel through aqueous solutions. Greenbowe (1994) developed computer animations that illustrate the migration of cations and anions in the salt bridge of an electrochemical cell. Burke

Ebenezer et al. (1999) conducted a study to examine the effects of these computer animations and the conceptual change approach on student understanding that electrons do not travel through aqueous solutions. The results of this study suggest that the conceptual change approach is generally effective at preventing or dispelling the student misconception that electrons flow in aqueous solutions. Additionally, they report that the use of animations appears to be helpful when the questions require students to visualize chemical processes on the molecular level. The foregoing claims made in physics and chemistry studies substantiate my belief that computer animation of the solution process would be an effective way to incoporate students’ conceptions of dissolving. Because understanding the submicroscopic processes of solution chemistry is important for writing ionic equations and the study of electrochemistry and acids and bases, it is imperative that we identify useful ways to depict the solution process. Hypermedia offers much promise in this regard because it fosters “flexibility in the structuring of knowledge” (Gabel, 1994) to negotiate with students the scientific conceptions. FOCUS QUESTIONS Based on the functionalities of the hypermedia for chemistry learning, two focus questions are outlined for the study: 1. What kinds of evidence suggest that a group of 11th grade students changed some of their prior instructional conceptions about the solution process of table salt as a result of animations in a hypermedia environment? 2. What are some of the areas of success and difficulty that 11th grade students experienced while learning solution chemistry in this particular hypermedia environment? There is a great potential for hypermedia in science education (Marchionini, 1988) because the designer can assess students’ prior conceptions, develop databases of students’ conceptions, and develop databases of activities and learning strategies that would provide students with experts’ conceptions. However, this potential must be explored. This study is an attempt to explore and assess students’ conceptions and negotiate meaning within the hypermedia environment. The hypermedia environment can foster the development of “common knowledge” (Edwards and Mercer, 1987) about the solution process of table salt. Common knowledge development in this study refers

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Dissolving in the Hypermedia Environment to the “socially constructed and accepted knowledge. In common knowledge development, the teacher negotiates with his/her students to arrive at shared understandings” (Ebenezer and Connor, 1998, p. 42). Students and teacher must agree over understanding of a chemical concept because chemical knowledge is determined by “chemical societies” and has a status of permanence. In this study, the teacher negotiation of chemists’ knowledge with students was in the hypermedia environment. Although, students were involved in exploring and constructing knowledge in the hypermedia environment, they had to arrive at a particular chemical understanding. DATA COLLECTION AND ANALYSIS Seventeen out of eighteen 11th grade (about 17 years of age) students in a chemistry class took part in this study. Of these 17 students 7 were female and 10 were male. Except for one colored male older student, all students were white Canadians. Whether or not students were research participants, all of them were expected to participate in learning experiences planned for the solution chemistry unit that consisted of twelve lessons. The first research activity in this traditional chemistry class consisted of Task A: students individually exploring their conceptions of sugar dissolving in water. Materials for Task A (sugar, water, a beaker, and a stirring rod) were given to each student. Each student was also given a paper that outlined the steps for carrying out the exploration activities as well as the questions: “What do you think might be happening to sugar and water in the beaker? If you were to wear an imaginary pair of goggles and actually see what is happening in the beaker, what would you see? Describe what you see and draw a picture of what you might see.” Students’ responses to these questions were collected. Each student’s written account and their diagrams were analyzed and the researcher constructed phenomenographic despcriptive categories. Refer to major studies in chemistry for how the phenomenographic categories may be arrived (Ebenezer and Erickson, 1996; Renstr ´ om ´ et al., 1990; Tullberg et al., 1994). On the next day of classes, the teacher and the researcher helped students become aware of their personal ideas. With this background, in their first lesson students moved through a hypermedia lesson on “melting” because students had difficulties distinguishing between melting and dissolving, both macroscopically and submicroscopically. This lesson

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77 and subsequent lessons in a HyperCard environment were conducted in the mathematics computer lab that was specifically booked for this research. The mathlab contained four 6100 Macintosh computers with HyperCard 2.2 Player. The researcher set up her PowerBook 520C laptop and her desktop Macintosh 11 SI. There was also a computer brought from the science department. Thus, seven computers were available for use by 18 students. None of the students had used HyperCard before. Because there were three students to a computer and they had no prior experience using HyperCard, they were given a booklet called “Personal Solution Chemistry Journal” to record their answers, understandings, and feelings. The card numbers in the HyperCard environment matched with the special journal provided for them. However, not every card in the stack was included in this journal for economy of space, paper, and printing costs. The students were asked to surf through the cards available in the stacks and at the same time were asked to write and draw their understandings and conceptual ideas from the use of the chemistry stacks. Some students tried to type on the computer itself, more for the fun of it. HyperCard became the research instrument because data concerning students’ understandings and negotiation of meanings were collected through this means. In the second lesson, students studied the nature of solutions. In the third lesson, students observed a teacher demonstration of an oridnary chemical change (magnesium ribbon in water) and the teacher held a discussion on the difference between dissolving and chemical change. The fourth lesson consisted of the students working through a hypermedia lesson on “dissolving,” and is the focus of this article. It must be noted that the addition of salt to water was the example used to study the solution process in the HyperCard environment although we used the addition of sugar in water in the initial exploration activity. The example of adding salt to water was intentional because the main focus was on the study of ionic solids in the water environment. A previous study (Ebenezer and Erickson, 1996) has shown that the students’ conceptions for the addition of sugar or salt to water are common. Furthermore, it is easy to explain the solution of ionic compounds and then compare this with polar molecular compounds such as sugar. Like intelligent tutoring systems, the hypermedia environment on dissolving guided the students to achieve the intended understanding, certain pedagogical principles were followed. The teaching and learning strategies included in the hypermedia were

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78 “prediction, observation, and explanation” diagrams and journal writing. More specifically, the intention was to develop common knowledge through cards pertaining to macroscopic, submicroscopic, and symbolic knowledge. Intentionally a very simple hypermedia environment for salt dissolving in water was developed. This environment reflected the basic principles of hypermedia. The buttons in each “node” or card enforced the movement to the subsequent node because of the hierarchy of solution chemistry content knowledge. This characteristic of hypermedia enabled students to go forward and backward to see connections among different types of knowledge in chemistry: the macroscopic, the submicroscopic, and the symbolic (Johnstone, 1991). In addition, a click on the button animated depictions of the solution process. The students were able to play the animation any number of times. Students could actually alternate between macroscopic and submicroscopic knowledge in this Hypermedia environment. It was possible for students to focus their thinking on different knowledge types in chemistry and determine relationships among these. Design of the hypermedia learning environment was based on my goal as the designer. Because this hypermedia environment is developed for students to use with a particular chemical content in mind, it was more specific, structured, and goal based. Students’ interaction with the hypermedia environment in this study was limited because they were “expected to understand the domain in particular ways” (Winn, 1992, p. 207). The chemical knowledge needed to be represented and organized, and my hypermedia on dissolving had the potential to “represent subject matter knowledge and model the structure of knowledge” (Marsh and Kumar, 1992, p. 27). Hypermedia content was developed to assess students’ conceptions and present experts’ conceptions so that students had opportunities to change, modify, or reject their initial ideas. A HyperCard stack on dissolving table salt in water was developed to help students understand that dissolving is a chemical phenomenon consisting of hydration of two electrochemical species, namely, sodium and chloride ions. Both macroscopic and submicroscopic views were explored and negotiated. The HyperCard lesson on dissolving consisted of macroscopic, submicrosopic, and symbolic ideas. In this article I describe only the submicrosopic view and the symbolic with the aid of selected cards that depict these types of knowledge visually.

Ebenezer Cards 33–35 contained the following information: “Imagine that you have an imaginary microscope so powerful that you are able to see salt dissolving in water. Write your imaginary microscopic view of salt in water. Draw a diagram to illustrate your imaginary microscopic view of salt in water.” Cards 38–42 present animation of the “microscopic” view of salt dissolving in water. Card 38 (Fig. 1) shows the “microscopic” view of sodium crystal in water (before stirring). Card 42 (Fig. 2) indicates the hydration of sodium and chloride ions. Card 44 Through text and diagrams, (Fig. 3) illustrates the hydration of sodium and chloride ions. Card 45 (Fig. 4) is similar to Card 44, but it includes an ionic equation. I wanted the students to understand the theory behind the ionic equation. Cards 46–48 contained the following instruction: “How does the foregoing “microscopic” view compare with your personal theory? Could you now write a “microscopic” view of table salt dissolving in water? Write your “microscopic” view of salt dissolving in water. Draw a diagram to show a “microscopic” view of salt dissolving in water. The term microscopic is in quotes because it refers to the submicroscopic particles.” FINDINGS Preteaching Descriptive Categories of Dissolving: Sugar/Water Task Prior to the negotiation about dissolving of table salt in the Hypermedia environment, seventeen 11th grade students (7 female and 10 male) individually explored their conceptions of the sugar/water system (for details of sugar/water system see Ebenezer and Erickson, 1996). However, on account of students absences in class, only 15 students’ have been tracked. Table I indicates the frequency distribution for pre-teaching descriptive categories of dissolving for sugar/water task. Images Four students used “images” (attacking, decay, falling apart, landslide, and snow flakes) to describe the solubility of sugar in water. For example, notice Cole’s depiction of the sugar in water in terms of images: “decay” and the “building falling apart.” What is important to observe here is “the function images play in the learning of science” (White, 1988, p. 29). Images

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Fig. 1. Card 38. “Microscopic” view of sodium crystal in water.

can be self-invented or taught by others. Studies indicate that “people vary in the intensity with which they experience imagery . . . across the senses” (p. 30). Some are able to see pictures or visualize more readily of words that they hear, talk, read, and think than others are. Because images are trigerred readily in most minds, it is important to use imagery in science class. In his theory of multiple intelligence, Gardner (1993) advocates the development of imagery in students.

The Transformation of a Solid to a Liquid Six students thought that the solid (sugar) was transforming into its liquid state. There were three different variations of this conceptualization: (a) “sugar particles broke up into very small pieces,” (b) “sugar changed from a liquid to a solid,” and (c) “the heat would cause the particles of the sugar to get smaller and they would move further apart.” For detailed

Fig. 2. Cards 38–42 in animation. Card 42—Hydration of sodium and chloride ions.

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Ebenezer

Fig. 3. Card 44. When table salt (sodium chloride) is added to water, it dissociates into sodium (Na+ ) and (Cl− ) ions. Water molecules surround the sodium and chloride ions. This process is called hydration.

analysis of this category of description see Ebenezer and Erickson (1996). The Chemical Combination of a Solute and Solvent Four students conceptualized that the chemical combination of a solute (suagr) and a solvent (water) was taking place. These representations consisted of diagrams and equations as shown in Table I. For detailed analysis of this category of description see Ebenezer and Erickson (1996). The Breaking of Attractive Forces in the Solute One student mentioned the aspect of breaking the attractive forces in the solute. This student has

some notion of the beginning stages of the solution process. What is not clear is whether or not his meaning refers to the separation of the sugar molecules or the separation of the sugar molecules into its individual atoms (carbon, hydrogen, and oxygen). The Solute Occupying Spaces Between the Solvent Molecules Three students theorized that the solute was occupying the spaces between the solvent molecules. The three diagrammatic respresentations were different: (a) many solute particles around one water molecule (Brian), (b) a neat arrangement of solute particles between water molecules (Eddy; not shown in Table I), and (c) a random arrangement

Fig. 4. Card 45.

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Dissolving in the Hypermedia Environment of solute particles between water molecules (Marvin). With respect to this conception, by contrast, in Renstr ´ om ´ study (1988) as well as in Ebenezer and Erickson’s study (1996), students talked about sugar occupying air spaces rather than spaces between water molecules. An understanding of students’ foregoing conceptions will enable us to see the nature of constructing knowledge in the hypermedia environment. This article describes and interprets students’ progressive conceptions as a result of the hypermedia intervention.

81 bination, and salt occupying spaces between water molecules) for salt/water, but he had only one conception for the sugar/water system. Some students added more conceptions, others maintained their original conceptions. Some students’ conceptions were different, but may not be accurate. This conceptual change, correct or inaccurate, and the development of additional conceptions could be attributed to students’ group work in the hypermedia environments. Students’ Conceptions of Melting Versus Dissolving

Description of Progression in Terms of the Hypermedia Intervention From the results gathered from their personal journals and the HyperCard for the salt/water task in the hypermedia environment, I developed categories of description at several key points: (a) students’ conceptions of salt in water, (b) students’ conceptions of melting versus dissolving, (c) students’ personal conceptions versus hypermedia conceptions of dissolving, and (d) students’ conceptions of dissolving. Tables II through V clearly show the organization of students’ conceptions into descriptive categories, students who belonged to each category, the number of students, examples of students’ written accounts, and students’ diagrams. To begin with, I discuss the preteaching descriptive categories of dissolving of sugar/water task. Students’ Conceptions of Salt in Water To learn the solution process students were expected to go through the hypermedia lesson on salt dissolving in water. According to Table II, 4 of the 15 students who took part in learning the dissolution of salt in water, despite the instruction on melting in the hypermedia environment (Lesson 1), gave an explanation that salt was becoming a liquid. Despite the teacher’s demonstration on chemical change (Lesson 3), 10 students stated that there was a chemical combination between the salt and the water. Seven students now thought that salt was occupying the spaces between the water molecules. Some students had more than one conception the same system as usually pointed out in phenomenographic studies (Ebenezer and Erickson, 1996; Linder and Erickson, 1989; Renstr ´ om ´ et al., 1990; Tullberg et al., 1994). For instance, Brian had all of the three conceptions (melting, chemical com-

Students made the following distinctions about melting and dissolving in the hypermedia environment in Lesson 4 on dissolving (Table III).Three students still maintained that both melting and dissolving consisted of a phase change. Two students stated that melting was a physical change but maintained that dissolving involved chemical combination. Five students made distinctions between melting and dissolving in terms of temperature change, the former process is the result of an increase in temperature while the latter process consists of no temperature change. But, we must remember that dissolving involves heat of solution and energy changes. Three students applied the kinetic molecular theory for melting and stated that the dissolving solute occupies spaces between the solvent molecules. Students’ Personal Conceptions Versus Hypermedia Conceptions of Dissolving After showing the solution process in animation in the hypermedia environment, students were asked to express the difference between their own personal conceptions and the conceptions presented in the hypermedia environment on dissolving. Consider their responses in Table IV. Three students said that their conceptions and the conceptions presented in the hypermedia environment are the same, although these same students thought that a chemical combination takes place between salt and water. Four students felt that their theories were the same but the theories illustrated in the hypermedia were sophisticated. For example, note Brian’s statement: My theory is the same as the above microscopic view. In my theory I predicted that the salt would become part of the water molecule but in the diagram on the computer it just showed the water molecule surrounding the salt particles.

Christina Laura Larisa Mila Erica Julie

Kenny Larisa Mila Don

The transformation of a solid to a liquid

The chemical combination of a solute and a solvent

Names

Cole Kelly Jerry Carmen

Images

Descriptive categories

The sugar has dissolved the water. The sugar isn’t completely gone. It has become part of the water. There is still sugar there but you just can’t see it. The sugar and water molecules have combined to become one molecule. So this water appears to be the same water you started with, but it is actually a completely different substance. It’s like when you add Kool-Aid to water. You started with water and you ended up with water, but water that has sugar in it (Kenny).

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I think that as the sugar is added to the hot water the heat would cause the particles of the sugar to get smaller and they would move farther apart because they obtain heat the faster they move (Laura).

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The sugar changed from a solid to a liquid. The sugar hasn’t disappeared but just changed form and was mixed with water (Larisa).

The sugar particles broke up into very small pieces so you could no longer see them with the naked eye (Christina).

Diagrams

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Student’s expressions If I could see what was happening when the sugar decays in the water, I would see the bonds falling apart and the sugar coming apart, somewhat like a building falling apart (Cole).

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4

Frequency distribution (N = 15)

Table I. Preteaching Descriptive Categories for Sugar/Water Task

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82 Ebenezer

Deepmar

Marvin Brian Eddy

The breaking of attractive forces in the solute

The solute occupying spaces between solvent molecules

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The sugar particles will occupy the spaces between the water molecules. The hot water becomes soluble with sugar, sugar becoming one with the water molecules (Brian).

All of the sugar dissolved in the water. It looks like there was nothing in it. All of the sugar molecules have separated from each other and have gone in between the water molecules. As you stir it there are no spaces exposed to the sugar and therefore more of the sugar dissolves (Marvin).

The individual crystals of sugar are being separated from the cube and start blending with the water. The water breaks down the attraction forces between the sugar molecules. The sugar molecules are “diffusing” into the water until the concentration is equal (Deepmar).

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The sugar molecules are broken as a result of a chemical reaction that takes place when sugar is placed into water. The broken pieces then bond with the water molecules and form a clear liquid that doesn’t have any physical changes but experiences many chemical changes (Don).

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Brian Carmen Christina Larisa

Brian Carmen Cole Don Deepmar Milly Kenny Larisa Mila Jerry

The transformation of solid to liquid

The chemical combination of solute and solvent

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There is a chemical reaction taking place here. The water and the salt are being forced together to create salt water. The salt molecules attach themselves to the water molecules in small particles. They are not lost, they are simply microscopic (Mila).

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There is a chemical reaction taking place here. The salt and the water molecules are combining together. The water molecules are forcing apart the salt molecules making it seem like it disappeared. The salt molecules attract to the water molecules (Kenny).

The salt molecule joins with the water molecule. When all the water molecules are joined with the salt molecules there might be salt left over (Carmen).

Place a solid into a liquid—solid becomes a liquid (Brian).

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Student’s expressions

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Descriptive categories

Table II. Descriptive Categories for Salt/Water Task

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Frequency distribution (N = 15)

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The solute occupying spaces between the solvent molecules

Brian Christina Deepmar Eddy Kelly Laura Marvin

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I think that the salt will dissolve in the water. The salt is the solute and the water is the solvent. The molecules of salt will move in between the water molecules (Laura).

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The salt molecules move into the spaces between the water molecules. If there are no more spaces left the salt would fall to the bottom of the container (Eddy).

It is there, you just can’t see it (Christina).

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Ebenezer Table III. Students’ Distinction Between Melting and Dissolving After Teaching Frequency distribution (N = 15)

Descriptive categories

Names

Phase change—phase change

Brian Carmen Christina Cole Don

3

5

Kinetic molecular theory— solute occupying spaces in between the solvent

Deepmar Milly Kelly Laura Jerry Eddy Larisa Marvin

Phase change—chemical combination

Larisa Kenny

2

Phase change—phase change

Increase in temperature—no increase in temperature

2

3

In particular, Eddy admitted, “it is pretty close to my diagram. I did not know the (water) molecules separated from each other and attracted the +− [ions of sodium chloride].” Christy still maintained the phase change view and Kinetic Molecular Theory (see Table IV for her

Student’s expressions Melting is when a substance changes phases—goes from a solid to a liquid. Dissolving is putting a solid into a liquid and then changes to a liquid (Brian). No, melting is not the same because melting involves a phase change as well as chemical and physical changes. Dissolving doesn’t have a phase change (Don). No, it’s not the same; when we melt something we are changing the temperature and we are not adding anything to it. When we dissolve something there is no temperature change, but we are adding a substance in the solution (Milly). Melting is when molecules separated farther when heated to a correct temperature and are allowed to move around in the liquid. Dissolving is when molecules are dissolved into a particular liquid and are in between the spaces of the liquid molecules (Eddy). No, melting is a physical change; it changes phases from solid to liquid. Dissolving is when a solute is added to a solvent and a chemical change occurs (Larisa).

statment). Four students admitted that they had changed views. Except for Laura, the other three students until this time thought that a chemical combination was taking place between salt and water, but now they have different views. For example, note Mila’s statment: “The salt molecules are not attaching

Table IV. Comparison of Prior Personal Conceptions with Hypermedia Conceptions of Dissolving

Descriptive categories No response Basically the same

Similar but sophisticated in hypercard

Kinetic molecular theory

Changed views

Names

Frequency distribution (N = 15)

Student’s expressions

Carmen Jerry Cole Deepmar Milly Brian Kelly Eddy Marvin Christina

1 4

No response (Carmen). They are basically the same (Jerry).

4

The computer diagram was a little more sophisticated but the meaning was the same (Kelly).

1

Don Kenny Laura Larisa Mila

5

The molecules of salt separate until the concentration is the same as the water. It acts like a gas. In a room it will continue to spread out until it has evenly filled the space provided (Christina). I now think the salt particles do not get smaller but join water molecules to chemically change and form saltwater (Larisa).

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Dissolving in the Hypermedia Environment themselves to the water molecules. The water is in fact forcing the sodium chloride atoms away from each other to prevent them from combining and creating table salt.”

Students’ Conceptions of Dissolving Students were finally asked to write their “submicroscopic” views of dissolving salt in water. They were also asked to depict their understandings with diagrams. The two categories of students’ conceptions of the dissolution process of salt are (a) the chemical combination of solute and solvent, and (b) the solute occupying spaces between the solvent molecules. These categories of descriptions are shown in Table V. Three students showed chemical combination depiction. They showed the salt attached to the water thus forming salt water. The rest of the students (N = 12) showed conceptions that are somewhat similar to the characterizations provided in the hypermedia environment. But students’ depiction of hydration ranged from “flowerlike” to the proper orientation of water molecules toward the ionic species. Only one student’s expression and representation were closer to the expert’s model compared to any other student in his class. Some students have shown proper orientation of water molecules. They have also represented the “cages” of sodium and the chloride, but they do not assign charges to the ionic species. Some students got confused with terminologies such as molecules, atoms, and ions. This confusion is not surprising; many studies confirm this finding (Garnett et al., 1995).

DISCUSSION The 11th grade chemistry students’ expressions and diagrammatic representations were useful to “see” what they were thinking about the solution process. Evidence of students’ expressions and representations indicate that the animations in the hypermedia environment enabled students to visualize how melting is different from dissolving, how ions are formed, and how hydration took place. In subsequent lessons, students were successful in translating their understandings of table salt dissolving in water to the dissolution of other ionic solids in water. They were also able to write the corresponding ionic equations. Thus, the original objectives of developing hypermedia were achieved. Iverson (1995) claims that computers can have an immense impact on chemical ed-

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87 ucation in the classroom and chemical research. This author’s view is that students acquire a much more thorough understanding of chemical concepts when three-dimensional computer animations are used to illustrate molecular sturctures and reaction mechanisms: collisions, bond breaking, and bond forming. The chemistry teacher who collaborated on this study pointed out that the sequence of chemical concepts must be given serious consideration in this hypermedia environment. Second, the teacher felt the diagrammatic representation of the hydration of sodium and chloride ions (see Figs. 3 and 4) are confusing to the students and therfore produces other forms of “misconceptions.” Students came to the anticipated difficult part in the hypermedia environment on dissolving; that is, the submicroscopic aspects. The set of cards that depicted the submicroscopic process of solutions had very little textual information (see hypermedia environment in the Methods section). There were three areas of difficulty that the students encountered within the hypermedia environment: (a) the ion formation, (b) the polar nature of water molecule, and (c) the hydration process. Based on this knowledge, recommendations are outlined in this section. The chemistry teacher involved in this study also felt that certain representations should not be presented in the hypermedia environment. The hypermedia lesson on dissolving table salt in water created an ambiguous context because of the diagrammatic representations. Students got confused with the charge representation of an ionic solid such as sodium chloride and a polar representation of water molecules. Some students thought that water would separate into oxygen and hydrogen charges and attach to the sodium and hydrogen ions. For example, a student stated: “The negative electrons of oxygen are attracted to the positive electrons of sodium and the + H bond with − Cl atoms.” Although the polar nature of water molecules must be shown to represent how water molecules orient themselves to the sodium and chloride ions, the teacher pointed out that it is better to leave the representation of electronegativity out. The computer animations were created based on students’ prior conceptions and “goal conceptions,” similar to Hennessey et al.’s (1993), in which the authors use computer simulations to assist students to change from their prior conceptions network to goal conceptions network (Newtonian theory). In my study, students progressed through simple to complex qualitative reasoning. Students definitely indicated a change in their conceptions within the hypermedia

Laura Christina Mila Carmen Marvin Larisa Brian Kenny Eddy Deepmar

The solute occupying spaces between the solvent molecules

Names

Cole Milly Jerry Don Kelly

Student’s expressions

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The table salt made up of Na and Cl will break apart in the water. So you have two different (ions). The molecules of salt, Na and Cl, will be surrounded by water molecules. When all the water molecules are used up surrounding Na and Cl then you get a deposit of salt on the bottom Even though the two Na and Cl are attracted to each other, the water prevents the two from joining together (Larisa).

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If the space was larger, concentration would be less because the number of salt is the same. If there is more space for it to fill, there would be more leftover water (Christina).

The salt is dumped into the water. Then the salt molecules separate and become sodium and chloride molecules. Water molecules attach to these. The molecules become evenly spaced in the container (Kelly).

The table salt will dissolve the water forming salt water (Cole).

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Frequency distribution (N = 15)

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The chemical combination of solute and solvent

Descriptive categories

Table V. Postteaching Descriptive Categories of Dissolving

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The sodium and the chloride atoms break apart and the sodium removes an electron from the chlorine atom. This makes the sodium negatively charged and the chlorine positively charged. Since the oxygen atoms in the water are negatively charged, they are attracted to the positively charged chlorine atoms. Balls of water atoms (cages) are formed around the chlorine atoms. This explains why there can only be a certain amount of salt dissolved in the water (Deepmar).

As the salt dissolves the two chemicals will separate sodium and chlorine. A chemical phenomena—because after you dissolve the salt you can get back the original product (Brian).

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90 environment, mainly because of the animated form of the hydration process. At the end of the unit on solution chemistry, students’ expressions and depictions of the solution process ranged from most simple to somewhat complex. However, the students did not provide sufficient chemical details—descriptive, pictorial, or symbolic (equation form). Additionally, in their written expressions, the students used the terms such as molecules, atoms, and ions interchangeably. Chemistry students must be encouraged to realize the appropriate use of chemical language. For this to happen, students should understand the meaning of these theoretical constructs. Students should also be made consciously aware that there are different knowledge types in chemistry (Gardner, 1991; Johnstone, 1991; White, 1988). Students should be able to interrelate different knowledge types in open-ended questions without the teacher giving cues. While teaching a unit of study in chemistry, we must continually monitor and assess students’ progress in “multiple dimensions of reasoning” (Gardner, 1991) to guide curriculum and pedagogical decisions (Gitmore and Duschl, 1998). The findings show that hypermedia environment developed for this study requires further refinement. What I have learned in this study has helped me to develop a different hypermedia environment with multiple nodes and multiple links to various types of knowledge in the dissolution process of water (Ebenezer, 1996). This network structure offers students opportunities for choice and flexibility in learning the content. However, I think that the content knowledge can be traversed sequentially if a student needs to progress through macroscopic to submicroscopic knowledge levels in chemistry. For conceptual change or goalbased teaching, a hypermedia environment with a simple organizational structure might be more useful than a rich network of interconnections. The hypermedia lesson on “dissolving” used for this study presented limited textual material with the intention that these spots would give students an opportunity to ask questions, and for the teacher to begin negotiating with students. The conversation did begin and end with a long teacher explanation of the same material to three different groups at three different times within the same period. Certain pauses were intentionally created so that students would share their ideas with the rest of the class. The nature of the classroom as well as students reaching the spot at different times did not allow for peer interaction. There was evidence of some discussion within the three-member group according to

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Ebenezer the data that were obtained, but at no point did the class get together for an “interactive discussion” of the Erickson sort (1992) of problematic situations in solution chemistry. When students work within the hypermedia environment, is it plausible and effective to negotiate meanings with the teacher? Should the negotiation of meanings through the hypermedia and the studentsteacher negotiation be mixed? I think, that text and QuickTime movies must be included in a hypermedia environment so that students can refer to this knowledge if needed. A chat line is also necessary so that students can carry out peer discussions within the hypermedia environment. If the teacher is also on the chat line, the teacher will be able to negotiate meanings with the entire class, small groups, or indivudal students. These features of a hypermedia environment are characterized in a software called “Salt Dissolving” (Ebenezer, 1996), developed using a hypermedia program called Macromedia Director 4.0. This software is yet to be assessed in a chemistry classroom context to make further claims about the potentials of hypermedia in conceptual change learning in chemistry. Expectations of a hypermedia environment might be too ideal in most of the chemistry classrooms that are not computer “rich.” An alternative solution is for the teacher to have students pause at important sites and carry out a large group “interactive discussions” with students. In this study, the teacher did follow up with a discussion; however, it did not characterize the elements of an “interactive discussion.” If chemistry is taught within a constructivist paradigm, teachers ought to make a genuine effort to learn other types of teaching strategies such as “interactive discussion” and “journal writing” where students can raise questions. Explicit links must be made between the animated form of the solution process in the hypermedia environment and the writing of ionic equations. The solution process must be verabally explained by students. For the dissolution of each ionic solid, students should write the formula, depict the solution process, and write the ionic equation so that they can see the connections among these types of knowledge representation. If students and the teacher are just beginning to learn to use hypermedia environments, chat lines, and other technologies, and even otherwise, the computer environment is necessary for chemistry learning. A large group interactive discussion outside the hypermedia environment is crucial. For example, students can take turns and write the ionic equations

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Dissolving in the Hypermedia Environment on the board. During this time, the teacher must engage the other students to actively critique the knowledge representations. An alternative method might have students peer teach in a dyad (each student takes the role of the teacher and the leaner). Each student can actually come prepared to teach his or her peer. Peer teaching and coaching returns ownership to students. If there is some kind of extrinsic reward for the students such as bonus points, they are forced to do additional reading, ask pertinent questions, be mentally active in class, and regularly attend class. A goal in chemistry teaching and in all learning must be to help students become accountable for their own leaning. However, this type of learning needs a mind change and a “heart change” in both teachers and the students—chemistry content must not be delivered but experienced. Appropriate experiences must be created so that students will do most of the chemistry “talk” and “walk.” A supportive environment must be provided so that students will not be intimidated to share as well as openly negotiate their ideas. Students’ personal understandings of chemical concepts must be systematically brought to open in a supportive environment so that students will compare their own conceptions with their peers as well as the experts. Although the hypermedia environment is suitable to depict the chemical processes, negotiation of students’ conceptions must go beyond the electronic medium if facilities are constrained. Nodes in hypermedia should lead to other forms of learning chemistry so that a balance will be maintained between the electronic platform and other approaches to learning. Christopher Dede, a professor of Information of Technology, argues that new technologies can help transform schools if they are used to support new models of teaching and learning—models that characterize sustained community-centered constructivist classrooms for learner investigation, collaboration, and construction (O’Neil, 1995). ACKNOWLEDGMENTS This research project is supported by SSHRCC (No: 332-2550-01-600). REFERENCES Abraham, M., Williamson, V., and Westbrook, S. (1994). A cross age study of the understanding of five chemistry concepts. Journal of Research in Science Teaching 31: 147–165. Alesandrini, K. L., and Rigney, J. W. (1981). Pictorial presentation and review strategies in science learning. Journal of Research in Science Teaching 18: 465–474.

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