The results showed that collaboration did enhance learning and that blending cooperative learning with closed-lab instruction in computer science was viable.
J. EDUCATIONAL COMPUTING RESEARCH, Vol. 20(3) 259-277,1999
USING SIMCPUIN COOPERATIVE LEARNING LABORATORIES* JANET MEI-CHUEN LIN CHENG-CHIH WU HSI-JEN LIU National Taiwan Normal University
ABSTRACT
This article reports the research findings of an experimental design in which cooperative learning strategies were applied to closed-lab instruction of computing concepts. SimCPU, a software package specially designed for closedlab usage, was used by 171 high-school students of four classes. In contrast to the students in the control group who operated SimCPU individually, students in the experimental group formed threesome teams to learn the CPU-related concepts by operating SimCPU cooperatively. The results showed that collaboration did enhance learning and that blending cooperative learning with closed-lab instruction in computer science was viable.
INTRODUCTI0N
Learning hardware-related knowledge through laboratory work has long been a recognized part of courses such as computer organization, logic design, and microprocessor design. These laboratories are intended to help students link theory with practice and also give students the exciting experience of actually producing a piece of hardware that “operates.” In recent years, however, more and more closed labs have been created and implemented for software-oriented courses including computer programming [1-31, operating systems [4], algorithms [5, 61, and so on. Closed laboratories of this sort are quite different from the above-mentioned hardware laboratories or laboratories typically associated with natural science courses. The laboratories designed for teaching software concepts
*This research has been funded by the National Science Council of Taiwan, the Republic of China, under grant number NSC 86-2511-S-003-034. 259
8 1999, Baywood Publishing Co., Inc.
doi: 10.2190/XTVU-L25N-6N6E-E6RG http://baywood.com
260 / LIN, WU AND LIU
usually make use of some tools that provide simulation or animation of abstract concepts. The tools are most often in the form of computer software packages because they offer better interactive power than other tools. An increasing number of research findings have supported the positive effects of adding closed laboratories to computer science cumculum. In a research study carried out previously, we designed two software packages for use in the closedlab settings. They are SimLIST for teaching linked lists and SimRE€UR for teaching recursion. The results we obtained from field testing SimLIST and SimRECUR were very encouraging, and the findings have been reported in [7]. Applications of cooperative learning to the classroom date back to the early 1970s. During the past three decades, specific cooperative learning strategies have proliferated. In his book, Cooperative Learning, Slavin reviewed ninety experimental-control studies and found that the effects of cooperative learning on achievement were clearly positive [8]. Such cooperative behaviors as cognitive elaboration, peer tutoring, peer modeling, and mutual assessment were cited as the contributing factors for the enhanced achievement. Slavin also identified several noncognitive outcomes of cooperative learning, which included increased students’ self-esteem, higher peer support for individual achievement, positive influence on students’ internal locus of control, higher proportions of class time spent on-task, greater linking of class and classmates, and increased components of cooperative and altruistic behavior. It is worth noting that none of the ninety studies reviewed by Slavin were related to computer science education. As we have discovered, there were indeed not many research studies that have been devoted to the investigation of using cooperative learning in computer science education. Nonetheless, more and more computer science educators have been calling for an increase of cooperative activities in the classroom. They stress that traditional computer science pedagogy which emphasizes individual skill rather than team effort is wrong, because it fails to prepare students for the team-oriented work style they are bound to face after graduation [9-111. In fact, a similar statement had previously been made by Rutherford and Ahlgren in Science for All Americans [12]. They pointed out that “the collaborative nature of scientific and technological work should be strongly reinforced by frequent group activity in the classroom” as “scientists and engineers work mostly in groups and less often as isolated investigators.” In an early study Webb showed that learning computer programming with LOGO could be accomplished successfully in the group setting [13]. Keeler and Anson used cooperative learning strategies in a software application lab course and found that both students’ performance and retention were significantly improved [14]. Yerion and Rinehart went a step further in providing guidelines for incorporating cooperative learning in computer science instruction [ 111. Prey described the favorable results of fitting cooperative learning into closed laboratories associated with four software courses [ 191. On the contrary, Sabin and Sabin’s study did not find significant improvement in students’ achievement and
USlNGSiMCPU / 261
attitude when using cooperative learning in an introductory CS course [lo]. Besides, Seymour applied cooperative learning in her Computer Aided Drafting course and found little difference in achievement between the treatment groups, even though students indicated that they liked to work together [151. The organization of the remainder of this article is as follows. First we give an illustration of the user interface and functions of SimCPU. Then we explain how the laboratory activities and worksheets were designed. After that is a detailed description of the experimental design. Finally, we present the results of the experiment and discuss its implications. In the end are our conclusions. SIMCPUAND THE LAB ACTIVITIES SimCPU
SimCPU has been designed as a supplementary instructional tool for teaching
How Computers Work, one of the major topics contained in the new guideline for a course called Introduction to Computers [16]. The course, although offered as an elective, is taken by most of the senior high school students in Taiwan. The contents recommended for the topic of How Computers Work include the basic computer model, memory, CPU, and execution of machine language programs. Constrained by the limited time (8 to 10 hours) allotted for the topic, it is unlikely that the instructors will cover each specific content in detail, especially not the CPU and the program execution parts, since they are considered more difficult to learn. In fact, the complexities involved in inter-operation of the various parts of the CPU in order to carry out a sequence of machine instructions are hard to cope with even for computer science majors in colleges. We have found that difficult topics like these are especially in need of the support of supplementary instructional software [ 171. Such opinion was apparently shared by many other computer science educators, because our survey has led us to a number of simulators which were all aimed at facilitating students’ understanding of computer organization and the execution of programs written in machine or assembly languages. Among the simulators are the one developed by Searls [18] and another by Simeonov and Schneider [19]. Both of these were based on the architecture described in Tanenbaum’s book on computer organization [20]. Tsai’s simulator [21], instead, emulated the hypothetical machine described in Brookshear’s book [22] which offers an overview of computer science. The simulator by Barnett [23] and yet another one by Lauckner and Lintner [24] were quite similar. Both simulators were based on a much more simplified computer model because both had been designed for use in computer literacy courses. Since the target users of our SimCPU were meant to be high-school students with little or no prior computer knowledge, our simulator is more similar to Barnett’s and Lauckner and Lintner’s. However, SimCPU contains many more sophisticated features such as zero flag
262 / LIN, WU AND LIU
and instructions for comparing contents in different registers. Furthermore, SimCPU has been developed for Windows and implemented in Visual BASIC. The purpose of SimCPU is to help students visualize how a typical computer executes a machine language program. It shows how main memory and the four special registers-the program counter, the instruction register, the accumulator, and the zero flag-change their contents as machine instructions are executed one after another. As shown in Figure 1, SimCPU provides a thirty-two-byte main memory for storing both the program and data. Since there are thirty-two cells in its memory, an address can therefore be represented by a pattern of five bits ranging from 00000 to 11111. Each machine instruction is one-byte long. The first three bits consist of the operation code; the last five bits make up the operand field. With three bits for the op-code, SimCPU can provide up to eight different instruction types, which are HALT, ADD, SUB, LOAD, STORE, COMP, JEQ, and JUMP. The program counter will contain the address of the next instruction to be executed; it therefore consists of five bits. Since the instruction register is used to hold the instruction being executed and the accumulator to hold temporary data resulted from a computation, it makes sense to make both registers eight-bit-long. The main screen of SimCPU is divided into the following six sections: 1. The Menu Bar: The menus to be selected are File, Edit, Translate & Load, Run, Reset, and Help. The File commands allow us to read and save program files; the Edit commands are for editing the assembly programs. The Translate & Load menu and the Run menu are rarely used because those commands are also provided as buttons on the screen. The Reset menu consists of commands for resetting the contents of the registers and main memory when necessary. The Help menu provides quick reference of the instruction set, the detailed explanation of each instruction type, and some sample programs. 2. Main memory: The cells are initialized to all 0’s when the system is first started. Its contents are changed after the machine code has been loaded for execution and also when data associated with a program are modified. The arrow appearing to the left of the memory always points to the next instruction to be executed. It is provided as an extra visual aid for users to keep track of the execution sequence. 3. The Edit Window: This window is for users to write and/or edit an assembly language program. The window may be scrolled up and down to make space for more instructions. However, the number of instructions in a program is still limited by the size of main memory. 4. The Machine Code Window: This window will remain empty until the user chooses to translate an assembly program. This window is included mainly to show the one-to-one correspondent relationship between an assembly instruction and a machine instruction.
USlNGSiMCPU I 263
s
m 9
264 / LIN, WU AND LIU
5 . The CPU State Window: The program counter, the instruction register, the accumulator, and the Zero Flag together represent a simplified view of the internal state of the CPU. The contents of these four special-purpose registers change as SimCPU cycles through the fetch/decode/execute phases for each instruction. 6. The Buttons Area: The four buttons located at the lower right comer of the screen are: Translate & Load, Single-Stepping, Run, and Caps Lock. The SimCPU Laboratory Since SimCPU had been designed intentionally for use in school laboratories, it was supplemented with a set of three lab worksheets. In each lab worksheet we clearly stated the learning objectives of the lab session and explained lab activities in easy-to-follow steps. The worksheets also contained the questions to be answered andor discussed during the labs. The respective themes of the three lab sessions were as follows:
L a b Session I: Execution of Sequential Programs with SimCPU A. Learning objectives: (a) To get familiar with the operation of SimCPU. (b) To know how a sequential program gets executed. (c) To understand the roles played by the program countec the instruction registel; and the accumulator. B. Programming examples provided: (a) Multiplication of a number by 2. (b) Summing two numbers.
L a b Session 2: Tracing Execution of Programs with Loops A. Learning objectives: (a) To know how loops in assembly programs are executed. (b) To understand the function served by the zeroflag in the CPU. B. Programming examples provided: (a) Calculating the sum of 1 through 4. (b) Modification of the program in (a) so it can handle more numbers.
L a b Session 3: Writing Simple Assembly Language Programs A. Learning objectives: (a) To be able to write assembly language programs. B. Problems to be solved: (a) Calculating the sum of the odd numbers between 1 and 11. (b) Multiplication of two integers. Table 1 shows a portion of the contents in the worksheet for Lab Session 1. It may serve to give our readers a glimpse of what our worksheets look like.
USlNGSiMCPU I 265
Table 1. Part of the Contents in the Worksheet for Lab Session 1 The program given below is to add together two numbers .Yand Y. and store the result in RESULT. Step~l:Open and read the file named "exl-2.a". Translate the program into machine code and load it in main memory. ( I ) Observe the contents of main memory and fill in the blanks. Address 0 I 2
3 3
5 6
T h e Assembly Code JUMP START: x 5 Y 3 RESULT 0 START. LOAD X ADD Y STORE RESULT HALT
blain Memory Contents
-
7 (2) Observe the contents of each of the following registers and f i l l in the blanks. , Instruction Register: , Accumulator: . Program Counter: Repeatedly click on the "Single-Stepping'' button until the program halts. With each clicking, observe how memory cells and the registers change their contents, and try to answer the following questions. (3) Observe the moves of the arrow to the left of main memory. It points to the cell at addrcss 0 when the execution of the program begins, and then it starts moving downwards and makes big jumps sometimes. Write down the addresses of memory cells i n the order they were pointed to by the arrow. The scqucncc: 0 3 (I) Observe the contcnts of each of the following registers when the program halts and f i l l in the blanks below. , Instruction Registcr: , Acc um ti lator: Program Counter: ( 5 ) During the cxecution of this program. did you noticc that one incniory ccll has changcd its contents? Which is i t ? Which instruction caused the change in that memory ccll? -_ (6) Whcn the execution of this program comes to an end. what is the h i t pattern storcd , its equivalcnt decimal tbrni? i n variable RESULT? (* blore s~epsgo liere. *)
wz:
. ..
Questions for Discussion I . Referring to Example I , can you modify the program by adding a singlc instruction to it so the new program will compute the result of "Multiply a nuinbcr by .3" instead'? 1. Example 2 showed you how to add together two numbers ..rand Y and store the result i n RESULT. I f you want to subtract Y from Xinstead, which instructions should be modified? 3 , How docs CPU know which instruction it should execute next? Is the scquence of execution exactly the same as the order in which instructions werc placcd i n main memory?
266 / LIN, WUAND LIU
THE EXPERIMENTAL DESIGN An experimental-control research study has been undertaken to investigate the effectiveness of using cooperative learning in closed laboratories. The independent variable of this research is the learning methods-i.e., individual learning vs. cooperative learning-while the dependent variable is students’ achievement in concept learning related to “How Computers Work.”
Subjects We used four intact classes of two different high schools in this study. The two high schools were selected from a total of thirty-eight high schools in the Taipei area. From these two schools we randomly selected two classes each for the sample. The total number of subjects was 171. It is worth pointing out that all students in Taiwan who want to get admitted to high schools have to take keenly competitive entrance examinations each year. The scores made by those students who get admitted to the same high school usually differ by approximately 10 points out of a total of 700. Besides, all high schools are required by the Ministry of Education to adhere to the principle of random assignment of students to classes after their admission. With such background in mind, we may reasonably assume that students in different classes of the same high school are comparable in terms of academic capability. Both of the schools we chose rank in the middle among all the high schools, but one is somewhat better than the other in terms of the admission scores. The reason for choosing two classes each from two different schools was to strengthen external validity of our study. As it turned out, similar results were obtained,just as we expected. At the time of this experiment all of the subjects had already finished the first semester of Introduction to Computers and were continuing with the second semester’s coursework, which includes the unit of How Computers Work. One class at each school was designated as the control group, and the other class as the experimental group. The distribution of subjects in each group is given in Table 2.
Table 2. The Distribution of Subjects
School A School B Total
The Control Group
The Experimental Group
Total
43 41 a4
44 43 87
87 84 171
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Procedures The experiment took place over three weeks. The students met once every week for two hours. The first hour was used for lecture and the second hour for lab. Therefore, each student participated in a total of three lecture-lab sessions. All the lectures were carried out in the classrooms and by the same lecturer. The contents covered in each lecture were closely tied to lab activities. For example, the lecturer would walk through a program similar to what the students were about to work on in the following hour in the lab. The students went to the computer room for laboratories. Students in both groups (experimentalkontrol) worked behind a computer in the lab. The length of time used by the two groups was also the same. Both groups were given identical lab worksheets at the beginning of each lab session. Students in both groups worked on the worksheets as a guide as they interacted with SimCPU. We may describe students’ behavior in the lab as continually repeating a cycle consisting of three phrases: read, operate, and write. That is, students read the instructions on the worksheet first, they then operated SimCPU according to what was specified on the worksheet, and finally answered questions related to that specific operation. The only difference in treatment is that students of the control group performed SimCPU lab activities individually, whereas students of the experimental group used SimCPU cooperatively. During the lab sessions the same lecturer was available as a source of advice and help for both groups. As can be seen from our description about SimCPU in the previous section, SimCPU was by no means a piece of software which would require much practice before one became skilled in using it. Even so, the first lab session was designed specifically to familiarize students with the operational details of SimCPU. We adapted the STAD (Student Teams-Achievement Divisions) method in assigning students of the experimental group to heterogeneous teams [8]. Each team consisted of a high achiever, a medium achiever, and a low achiever. The achievement was based on the final scores obtained by the students from the same course in the previous semester. To avoid the so-called “free-rider effect” or the “diffusion of responsibility problem” [8], each team member was assigned a specific role prior to each lab session. The roles are the leader, the operator, and the note-taker. The leader was responsible for coordinating team members and encouraging team members to participate in team discussion; the operator operated the computer and manipulated the software; the note-taker was responsible for collecting the data and noting key points of discussions. It was assumed that with task specialization each student would more likely be proud of his contributions to the group. However, to avoid the possible pitfall that students’ experience would be limited to the subtask to which they were responsible for, we deliberately arranged three lab sessions so that the team members could take turns in assuming each of the three different roles. There were a total of fifteen collaborative teams in School A and fourteen in School B.
268 / LIN, WUANDLIU
The Achievement Test
An achievement test was given following the experimental period to students of both groups. The test consisted of twelve trudfalse questions and eleven blanks for students to fill in. One point was assigned to each trudfalse question as well as each blank, thus the full score was twenty-three points. The truelfalse questions were to test students’ understanding of basic computing concepts including data storage, data representation, conversion between different number systems, and program execution. The fill-in-the-blanks questions were mainly to test students on their understanding of how a program got executed inside the CPU. This part was more directly related to their experience with SimCPU. The Cmnbuchk CoefJicient Alpha was used to determine the internal consistency of the achievement test. The value obtained was .83 with N = 171. The Questionnaires
At the conclusion of the three-week experiment all students were requested to complete a questionnaire (Table 8 in the next section) to express their opinions about closed lab activities. Students in the experimental group were further requested to fill out a questionnaire (Table 7 in the next section), which was aimed at evaluating the usefulness of cooperative learning. The Observation Sheet
All teams of the experimental group were monitored by means of direct observation. An observation sheet was used to record behaviors of group cooperation. After having examined the ten behaviors used in the Classroom Observation Instrument in Science Laboratory Activity (COISLA) developed by Chang and Lederman [25], we included only five of them, namely discussing, encouraging, observing, writing, and off-task, in our observation sheet, as shown in Table 3. The remaining five behaviors of COISLA were considered irrelevant to our lab activities. Each team in the experimental group had been observed five times during the three lab sessions, and each observation lasted one to two minutes. Any occurrences of the five behaviors were recorded by marking the tallies in the appropriate boxes on the observation sheets. Apart from direct observation, we had also randomly selected two teams of the experimental group for fullsession tape recording. The purpose of this is to supplement the frequency counts reflected on the observation sheets with a further understanding of the “substance” of collaborative behaviors. For example, we would like to know not only the frequencies of discussing, but also what was actually discussed during collaborations.
USlNGSiMCPU I 269
Table 3. The Observation Sheet for the Experimental Group Date:
Group No.
I
Leader
I
Operator
I
Note-Taker
Name Behaviors
First Time
Second Time
1
First Time
Second Time
First Time
Second Time
Discussing Encouraging
!
I
Observing
I
Writing Off-task
Pilot Study Before we go on presenting the results of the experimental study, we would like to make a detour to describe a pilot study that was conducted prior to the experiment described above. The purpose of the pilot study was to examine the feasibility of the experimental procedure as well as the instrumentation. Two classes of ninety-four students in a senior high school, other than schools A and B mentioned above, participated in the pilot study. The experimental procedure was similar to what was described previously except that in the third week the control class and the experimental class switched their roles. That is, the control class became the experimental class and received the treatment of cooperative learning, and vice versa. With this treatment switching, the students of both classes were able to experience both styles of learning and make comparisons between them. The pilot study revealed a number of problems in our original experimental design. In Table 4 we summarized the major ones and also described the modifications that were later made in our final design. A questionnaire survey conducted at the end of the pilot study included not only the questions listed in Table 7 in the next section, but also a couple of additional questions that asked students to compare the two learning styles in terms of learning interests and personal preferences. The majority of students expressed their liking for cooperative learning much more than individual learning.
270 I LIN, WUANDLIU
Table 4. Problems Revealed in the Pilot Study and the Solutions Problem Revealed in the Pilot Study
Modification Made in the Final Design
1. The team size of four induced "freerider effecr and was too crowded for operating a computer together.
1. The team size was reduced to three.
2. Inadequatearrangement of working
2. The working space for each team was farther apart from each other.
space for individual teams introduced mutual interference.
3. The dual role of observer and instructor
3. A researchassistant was engaged to
played by the researcher hindered careful observation.
take care of the observationjob.
4. Some parts of the lab worksheets were hard to understand.
4. Lab worksheets were revised based
5. The questions included in the achievement test were too many to be completed within the allotted time.
5. The contents of the achievement test were simplified.
on students' feedback.
RESULTS AND DISCUSSION Achievement Effects Tables 5 and 6 present the results of the statistical analyses for our study. Table 5 provides the descriptive statistics of the ANCOVA analysis. Table 6 shows the summary results of the ANCOVA analysis on the achievement test scores. As there is no pretest in the design of our study, we have used the final scores obtained by the students in the previous semester as the covariate in our statistical analysis. It can be seen from Table 5 that there is a significant difference (F= 10.24,p = .002) between the test scores of the experimental group (with the adjusted mean of 11.74) and those of the control group (with the adjusted mean of 9.3 1) in School A. In School B the scores of the experimental group (adjusted mean = 16.06) are also significantly higher than those of the control group (adjusted mean = 13.78), with F = 8.72 and p = .W. We can therefore conclude that cooperative learning did improve students' achievement in learning the concepts related to How Computers Work The result is consistent with the findings of Slavin [8] in terms of the achievement effects of cooperative learning. We conducted separate analyses for each school due to the following reasons: 1) different teachers were in each school, and 2) the previous course grades used as a covariate in our statistical analysis were graded by different teachers based on different criteria. Therefore, it did not seem adequate to combine the expenmentautreatment groups between the two schools. As we pointed out
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Table 5. The Descriptive Statistics of Posttest Scores of Students Under Two Learning Methods Posttest Score
Previous Achievement Score
School
Group
Number of Students
A
Experimental Control
44 43
11.77 9.28
4.14 2.86
73.68 73.12
4.09 5.89
11.74 9.31
B
Experimental Control
43 41
15.77 14.07
4.81 4.13
74.00 75.57
5.46 4.85
16.06 13.78
Mean
SD
Mean
SD
Adjusted Mean
Table 6. Summary Results of the ANCOVA Analysis on the Achievement Test Scores
School
Source
ss
df
MS
F
P
A
Between Groups Error
128.38 1053.57
1 84
128.38 12.54
10.24''
.002
B
Between Groups Error
106.20 986.46
1 81
106.20 12.18
8.72'
.004
' p < .05
before, School B is better than School A in terms of their admission scores. It is not surprising to find out that students in School B scored considerably higher in the posttest than those in School A.
Feedback on the Questionnaires The questionnaire for the experimental group contained seven closed questions and one open question related to cooperative learning. The answers given to closed questions were collated and presented in Table 7. The results showed that the majority of students in the experimental group agreed that cooperative learning allowed them to seek handy help and encouragement from teammates (Questions 1 to 3), which could not only reduce learning pressure but enhance friendly relationship between teammates (Questions 4 and 5 ) . In addition, cooperative learning was not considered a time-wasting activity (Question 7). However, students' overall feelings about cooperative learning were to some extent negatively influenced by the concern over uneven work sharing (Question 6). Apparently
272 / LIN, WU AND LIU
Table 7. Percentage of Students Who "Strongly Agree" or "Agree" with Each of the Statements Concerning Cooperative Learning Statement
School A
School B ____~
1. I was willing to seek help from my teammates when I encountered difficulties.
Average ~
97%
100%
99%
100%
100%
100%
87%
70%
79%
21%
23%
22%
5. I agree that cooperative learning can enhance friendly relationship between teammates.
93%
93%
93%
6. Some of my teammates did not participate in the activities.
34%
39%
37%
7. I feel that cooperative learning wasted
5%
21%
13%
2. I was willing to share what I knew with my teammates.
3. My teammates would praise me when I did some good work. 4. I experienced pressure when my team-
mates performed much better than me.
my time.
the "free-rider effect," against which we took precautionary measures, had not been totally eliminated. The open question in our questionnaire generated a variety of positive and negative comments about cooperative learning. The benefits identified were: 1. peer-tutoring, 2. improved efficiency of group working, 3. saving of learning time, 4. enhancement of friendly relationships between classmates, 5. reduction of learning pressure, and 6. an increase in motivation to learn. The negative comments included: 1. Talkative team members slowed down progress and distracted others'
attention. 2. Some students felt uneasy working with unfamiliar teammates.
USlNGSiMCPU / 273
3. Some team members evaded their responsibilities or relied too heavily on others. 4. Team members frequently disagreed on how to accomplish a certain task. 5 . High-achievers idled sometimes because of different learning speeds between team members. The summarized results of the questions concerning closed-lab activities for the two groups were shown in Table 8. It showed that students of the experimental group appreciated lab activities more than their counterpart in the control group. The results were as expected, because we felt that collaboration should at least offer more opportunities of peer-tutoring and help reduce anxiety generated by learning an unfamiliar software (i.e.. SimCPU). It was, nevertheless, a surprise to us that students overwhelmingly found the questions on the lab worksheets too difficult and that SimCPU were not very user-friendly (Questions 4 and 5). These feelings also partially explained the not so favorable outcome of students’ answers to Questions 1 and 2. The figures shown in Figure 8 reveal that students’ overall reactions to the lab activities were not very positive. The reasons may include the following: 1. high difficulty level of the target concept chosen for the experiment, 2. too many activities arranged for each lab session, 3. the not-so-friendly user interface design of SimCPU, and
Table 0. Percentage of Students Who “StronglyAgree” or “Agree“with Each of the Statements Concerning Closed-Lab Activities School A Statement
1. Lab activities were helpful to
School 6
Coop. Indiv. Coop. Indiv. Average
50%
40%
87%
68%
61%
57%
31%
77%
38%
51%
84%
74%
98%
71%
82%
11%
2%
43%
36%
23%
32%
15%
50%
32%
32%
my learning of related concepts.
2. Lab activities increased my learning interest.
3. The steps specified on the lab activity worksheets were easy to follow. 4. I knew how to answer questions on the worksheets without
difficulties.
5. I felt that SimCPU was easy to use.
274 / LIN. WU AND LIU
4. students’ low motivation for learning computer-relatedknowledge as it will not be tested in the college entrance exam.
Careful readers may have noticed a gap between the survey outcomes of the two schools. Students of School A were less appreciative of closed laboratories than students of School B. The percentages of students who “strongly agreed” or “agreed” with the statements were consistently lower for School A. A possible explanation for such a phenomenon might be that the computers in School A were rather outdated and inefficient at the time of the experiment. Therefore, students’ somewhat negative feelings toward closed lab activities might in part be due to the computer hardware rather than the software or the activities themselves.
Students’ Collaborative Behaviors As each collaborative team was observed for five times during the three lab sessions, the total numbers of observations were seventy-five for School A (with 15 teams) and seventy for School B (with 14 teams). By adding up the frequency counts of each collaborative behavior across all teams in a school, we obtained the data presented in Table 9. The figures on the two pementuge rows in Table 9 were obtained by dividingfrequency by the total number of observations. The figures represented how often a behavior was observed. With both schools, it reflected that “observing” and “discussing” were the most noticeable collaborative behaviors, and “writing” came next. “Encouraging” turned out to have been observed least often. Given the fact that the lab worksheets for SimCPU prescribed a sequence of observations for students to carry out, the high percentage of “observing” was fully understandable. The low percentage of “encouraging” could be attributed to cultural difference, as Chinese people tend to subdue their feelings, either positive or negative, toward others. An analysis of the contents recorded on the audiotapes revealed that discussions among team members were mostly about two things: 1) to determine what the operator should do next and 2) to explain the result of an operation to other team members. It showed that students benefited a lot from mutual discussions in terms of clarification of concepts. The “writing” behavior occurred not only for
Table 9. Students’ Collaborative Behaviors School
Discussing Encouraging Observing Writing Off-Task
A
Frequency Percentage
66 88%
8 11%
70 93%
40 53%
12 16%
B
Frequency Percentage
54 77%
7 10%
64 91%
46 66%
20 29%
USlNGStMCPU / 275
recording data on the worksheets but also for hand tracing program results. Table 10 shows some excerpts from the tape recording. CONCLUSIONS
The research findings reported in this article are about an experimentaldesign in which cooperative learning strategies were applied to closed-lab instruction of computing concepts using SimCPU. The findings showed that collaboration did enhance learning, as was often concluded in many other studies. Data obtained
Table 10. Excerpts from the Tape Recording Excerpt 1 Student A: Student B: Student A: Student B: Student A:
Excerpt 2 Student C: Student D: Excerpt 3 Student E: Student F: Student E: Student F: Excerpt 4 Student P: Student Q: Student P: Student R: Student P: Student Q:
Excerpt 5 Student J:
What does this mean? It means a "comparison." When the zero flag changes to 1, the execution will make a jump. But how come it jumps to a HALT instruction? My goodness, why did you put two HALTSin the program? Take it easy. Let's take this HALT out and run it again. What did I do wrong? You misspelled this word. It is M-U-L-T-I-P-L-Y,not M-U-T-L-I-T-P-Y. Where is TARGET(in main memory)? Here. It's at address 3. What's the value inside it? 00000101
What should be the result of this program? 1+3+5+7+9+11.
But it doesn't look right. You are looking at the wrong one. It's at address 4. Make a hand calculation yourself. It's 00100100, so it should be 22 + z5. Is it 36? 1 + 3 + 5 + 7 + 9 + 11. Yes, it's 36.
Should I keep on pressing "single-stepping" until the program counter reaches 12? Yes. Ithink so. Student K: Student J: But it jumps right over 12! It's so troublesome. 1'11 quit. Student K, L: Don't give up, please. We are in the same boat. Let's do it again.
276 I LIN, WU AND LIU
from the questionnaire survey revealed that students’ attitudes toward cooperative learning were mostly positive. With respect to the lab ingredient in this study, we have described in detail how the learning-instructional processes in closed laboratories were carried out in our case. Hopefully, what is reported in this article may prompt more researches on the design of lab activities andor lab worksheets so that closed laboratories will be used more effectively in computer science education. Welldesigned lab worksheets are indeed central to the success of closed laboratories, because the worksheets serve not only to structure lab activities, but also to focus students’ attention on critical concepts to be learned. It is also our hope that more high-quality software could be developed for use in closed laboratories. Interactive software such as SimCPU, which provides simulation or animation of abstract computing concepts, will increase students’ learning interest and, moreover, help them understand abstract concepts more easily. Such software differs considerably from conventional CAI (computer-assisted instruction) software, and it would be very helpful if general principles and procedures for designing such kinds of software could be proposed soon. What we experienced from this study is that students’ mixed reactions to the closed laboratory activities could be indicating a need for modifying SimCPU itself as well as the lab worksheets. We are currently working on a simplified version of SimCPU with the aim of cutting down its functions and making its user-interface more intuitively understandable. The accompanying lab worksheets will also be revised in order to reduce students’learning load.
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Dr. Janet Mei-Chuen Lin Department of Information and Computer Education National Taiwan Normal University No. 162, Ho-Ping East Road, S e c . 1 Taipei, Taiwan 106
