Appears in Computers and Graphics (January/February 1996), vol. 20, no. 1, pages 177-80.

Abstract

Student learning and the depth of the student's knowledge increase when active and group learning methods are employed in the classroom. Group learning has the additional benefit of preparing students for professional environments. Active and group learning strategies are discussed in general computer science course work and as applicable in the graphics class. Difficulties with active learning and techniques for dealing with these are also presented.

1. Introduction

Active learning [1] gets students involved in an activity in the classroom rather than passively listening to a lecture. This activity can be reading, writing, discussing or solving a problem. This is important, because student concentration declines after 10-15 minutes in a 50 minute lecture [8]. Group work enhances this by providing a formalized way for students to cooperate in the learning process. In computer science and computer graphics, this usually takes the form of programming assignments. Structured, in-class group activities are an excellent way to combine both active and group learning benefits.

The act of learning is not passive. As faculty, we learn actively. In preparing lecture notes, we read, possibly from many sources, compare what we have read with our experiences, synthesize the information into coherent notes, and develop examples that illustrate the concept. This leads to greater understanding of the material. Unfortunately, we then use this understanding to lecture to our students depriving them of this journey of discovery. By carefully involving the students in this learning process, we can increase student depth of understanding of the material, increase student comfort with the material, and improve student confidence. In most sciences, the value of active learning is already realized and implemented through laboratories, or in computer science, through programming projects. The ideas presented expand this to include activities in the classroom that replace the lecture or part of it.

If active and group learning is so successful, why is it not used more frequently? This is because there is a perception that classroom active and group learning has higher risks. There is fear that to use active and group learning content will have to be taken out, pre-class preparation time will be higher, and that it is not appropriate for large classes. Perhaps the largest fear though giving up control of the classroom -- a lecture lets the professor decide what to say when, where student centered activities may raise questions that the professor is not ready to answer.

These fears are real, but surmountable. To cover the content, give students the responsibility for learning the factual material so that they can apply it in the classroom discussion. I have had students write on course evaluations that they didn't need to read the book before class because I would tell them what they needed to know from the chapter. To assure that students read the material, they can be asked to prepare a short essay or begin the class with a short quiz. 

For faculty that re-use class notes year after year, developing these strategies will take more time than pulling notes out of a filing cabinet. In a field as rapidly changing as computer graphics, notes need to be done frequently enough that this should not be a concern. Further, as you develop ideas for active and group learning, you will find that they can be applied across a number of different courses.

Active learning strategies allow you to control the level of risk. By selecting short, highly structured and well-planned activities, the level of risk is fairly low. Involving students by asking a series of questions about the current topic allows the teacher to control the direction and content of the discussion but still makes students active. Breaking the students into small groups, and letting them independently solve a problem is a much higher risk but can prove to be highly rewarding.

There is a common problem that faculty frequently have when asking questions for immediate student response. They answer their own question or rephrase it too quickly. Rowe [6] has found that teachers at all levels typically wait less than one second before beginning to speak again. Rowe further found that when the waiting time was increased to three to five seconds, that students are more likely to respond as well as respond more completely, support their statements, and respond to each other. The number of student generated questions also increased. So, it appears that the more we restrain ourselves, the more our students will participate. This is reasonable, since if we are talking, our students are not likely to interrupt.

2. Active Learning in Computer Graphics

As mentioned above, strategies for the computer graphics classroom are equally valid in many other computer science courses. The strategies will be described generically and examples for the graphics classroom will be given.

Modified Lecture [1]

As was mentioned, student attention begins to decline after 10-15 minutes of lecture. Further, we have all been in lectures where something catches our attention, causing us to "miss" part or all of the next point. A low risk strategy to handle both of these is to lecture for 10-13 minutes and then take a 2-3 minute pause. During the pause, students can discuss their notes with the person next to them filling in gaps and correcting misunderstandings. Posing a specific question for the students to answer can lead to a classroom discussion. A good mechanism for this is "think-pair-share." In this technique, a question is posed to the students who then individually write an answer within a one to two minute time limit. Students then "pair" up and discuss their answers, possibly developing a new answer. The instructor can then lead the class into a discussion by asking a few pairs to "share" their answer with the class. A less risky method would be to pose a question chosen to lead into the next lecture topic and then use the shared answers as the bridge back to another mini-lecture.

In the graphics class, you could pose questions like:

What will happen to the highlights on this ball if we increase the coefficient of reflection?

How will this shadow change if the light source moves closer?

Why is it important to reduce the number of multiplications and divisions in graphics (or line drawing) algorithms?

There are obviously many other questions. The more concrete the subject of a question, the quicker it can be answered and the less risk it poses for the instructor. The more abstract the subject of a question, the better it will be to lead into discussion and the higher risk it poses. In all cases, the question should not just require the recall of facts. To help the development of higher order thinking, questions should ask for contrasts, comparison or parallels between two ideas in a way that requires more than the repetition of material from the lecture or readings.

Algorithm Tracing

Instead of tracing the execution of an algorithm in a lecture, break the students into groups and have them trace the algorithm. For example, to compare the DDA and Bresenham algorithms for lines, break up the class into groups of four students each. Assign one student as the algorithm tracer, one to keep track of the variable values, another to record the number of additions/multiplications performed, and the last to record the visual output. By providing each team with transparencies (with permanent grids) and markers, teams can compare the results of the two algorithms, and easily display their answers to the rest of the class.

Physical Experimentation

To understand computer graphics, one must understand the physical processes that it is stimulating. Though we look at things all the time, we do not tend to carefully look and analyze what we are seeing. This is probably especially true of students and probably much less true of computer graphics faculty. My attention will be captivated by light and shadows that are cast on a wall if the light source is not obvious. I find myself mesmerized by the relative positions of objects, shadows, lights, and reflective surface as I try to figure the complex path the light might be taking. The same is true of many other lighting effects.

Instead of explaining how lighting works, it would be more instructive to describe the types of reflections and refractions and then provide the students with flashlights (torches) and different types of objects and let them try to recreate the effects. This type of exercise is especially important because it will also get the student to begin visualizing particular effects and critically analyzing physical and computer generated images.

It is extremely important to develop the ability of students to mentally visualize three-dimensional objects, and their spatial relationship. Without this ability, students cannot determine whether the images their software creates correctly match their input.

Demonstration Software

Dino Schweitzer [7] has developed a series of demonstration programs that can be used in the classroom and are available through the ACM SIGGRAPH Computer Graphics Courseware Repository (via ftp from cgcr.gsu.edu, login:cgcr, password:cgcr). The topics covered include line clipping, color maps, boundary fill algorithm, line drawing, shading, 2-D and 3-D transformations and projections.

G. Scott Owen [5] has developed a system called "Hyper Graph" that is a hypermedia system he uses in place of a graphics textbook. This system includes not only written descriptions but also images and animations that the user can interact with.

Dividing the students into groups, you can ask them to predict what will happen to an image based on some process (e.g. scale followed by a rotation) or ask them what is necessary to cause a particular effect (e.g. shadow an object by repositioning a light source). Then in a laboratory or a classroom (with a projection unit) running demonstration software, the professor has a powerful tool to have students directly interact with the ideas of computer graphics. This set up also allows students to formulate "what if" questions as they are trying to understand an idea. For example, students trying to understand the rendering equation, with the proper software, can alter parameters and watch as the object(s) change appearance.

Care must be taken in any exercise where students are directly manipulating a demonstration program. The instructor must make sure that students think before using the program. The educational value of this exercise will be lost if the students just "hack" at the software until they find the answer. This exercise will not develop higher order thinking if students do not analyze the question, propose an answer, produce a result using the software, and then think about the relationship between their answer and the result. Repeated iterations of this process will further enhance its value.

3. Group Considerations

Most active learning exercises that go beyond Socratic questioning of students or use of the "think-pair-share" technique require groups. Group exercises pose an extra challenge in that group interactions add a level of complexity over which the instructor has only indirect influence.

There are measures that the instructor can take to positively influence group interactions. Studies have been done on group work, and [3] is an example. This section draws on this research and personal experience to develop recommendations that help groups succeed (or at least not completely fail).

Students

When you use active and group learning, you need to fully inform your students of the value of these methods, what you expect them to do, and that their involvement will provide them with beneficial results. You need to develop an atmosphere of cooperation between you and your students, as well as among them.

I find that letting my students know that I am taking risks for them and that this does not reduce my work (though it appears to) seems to help set the right tone. I go so far as to list myself as "Instructor/Guide" or "Instructor/Coach" on the syllabus. I further make it clear that I see examinations as the way for them to show me what they have learned rather than for me to show them what they haven't.

Students will also need some help in organizing their groups. I will usually give guidelines that, if followed, assure reasonable levels of participation by all. I will also frequently suggest roles (e.g., leader, time keeper, reporter/recorder) that the students should rotate through that should help the group process. The point is to share whatever strategies you feel will help.

Group Information

I form groups. Allowing students to form their own groups has two effects: it isolates students who have no friends in the class, and creates groups with low peer pressure. Even though it might seem that a group of friends might be more willing to work harder, the reality is that friends will cover for those not working, will be unwilling to discuss the problem with their instructor, and will not want to risk the friendship by pressuring a friend to work. In selecting groups, I will try and balance groups by grade point average (most important), gender, race, age, and major (in "service" courses). I will sometimes do a survey of student interests and create groups based on similarities to help group bonding.

Group size is important as well. Studies show that groups of between four and six are best. Smaller groups break down into factions or suffer if someone is absent. Larger groups do not allow enough individual participation and pose scheduling problems for outside activities.

Groups will take at least one half of the semester to become cohesive. For this reason, my groups are static and students only get out of a group by getting out of the course.

Evaluation

Students need early and regular feedback. In discussions, good answers should be praised and incorrect ones should be questioned, analyzed for misunderstandings, or critically evaluated. But if discussion is to be encouraged, the student shouldn't feel attacked by the professor. If a student answers incorrectly, I will ask him/her for elaboration with a simple, "why?", or ask the class for reactions to the answer. If it is partially correct, I will praise the correct portion before questioning the incorrect. This seems to create a supportive environment for all students, not just the respondent. To encourage discussion, I will let a few students answer before making any comments or asking further questions.

To encourage students to take the group work seriously and, therefore, benefit from it, group work should influence the course grade. It is recommended that group work should influence at least 20% of the grade with no single assignment accounting for more than 60% [3]. It is also important that there be some peer evaluation component, which seems to encourage personal responsibility and group cohesion.

Group Activities

Susan Feichtner and Elaine Davis [3] have studies student reaction to group work and have found that the following group activities appear to be ideal:

no more than one class presentation

less than three reports

between one and three group exams

They also found that students also appreciated having class time allocated to group activities.

4. Experiences

During the fall of 1992, 1993, and 1994, I taught a theory of computation course using three different methods. The Fall 1992 course was pure lecture, with the students completing 10 homework assignments, three term exams and a cumulative final exam. There was no group work. The Fall 1993 course included active and group learning in the form of classroom group problem solving, and group homework and exams. The number of homework assignments was increased to 20. The Fall 1994 course was the same as Fall 1993, except that the classroom problem solving was replaced by questioning from me. I would categorize these three course offerings as having no active learning (Fall 1992), high active learning (Fall 1993) and medium active learning (Fall 1994). (For more details on this study, see [4].)

Since I do not return final exams, I was able to use the exact same final exam all three years. After a regrade of the exams and a statistical analysis of student grade point average (GPA) and exam performance, I found a statistically significant improvement of exam scores when active learning was used. Further, the analysis showed that this was not due to a difference in the abilities of the students, since the course with the highest exam average had, by a slight amount, the lowest average of GPAs. Active learning had improved student performance by about 50%.

5. Further Examples

The examples of student centered learning presented below represent the full inclusion of active and group learning concepts and minimize lecture time. These classes take preparation that is different from that for a pure lecture. In the fall, 1995 semester, I will be teaching three courses using active learning. A computer graphics course could use adaptations of these forms.

My "Theory of Computation" and "Analysis of Algorithms" courses, will begin with the students (in groups) developing a list of questions that they had from the reading. They will then need to rank this in the order they want me to answer them. The questions must be more specific than "explain X." This process is allocated no more than 20 minutes. I will then answer as many questions as possible in the next 20 minutes (or less). For the remaining 35 minutes of the class, the students will work on a problem set, with answers turned in at the end of class.

The last course, "UNIX and C," meets once a week for fourteen weeks. In this course, each class will begin with a short (10 minute) group session for the students to clear up any questions. The next 10 minutes will be a true/false and multiple choice quiz on the reading material. Students will next take the quiz as a group while I grade the individual quizzes (about 10 minutes). The quizzes will be returned and students will then work in their groups on a programming exercise. The resulting program will be due the following week. There will be no midterm exams; however, all students will need to successfully complete a mastery exam at the end of the course, to show competence in the course material. (It should be noted that exam scanning equipment exists, that allows this structure to be used in large classes.) A colleague of mine, Frank Dinan, has successfully used a structure similar to this for his organic chemistry course [2].

6. Conclusion

Adopting active learning techniques can be risky for faculty, but the risk can be minimized. As your comfort level with active learning increases, riskier strategies can be tried. Though the loss of control can be scary at first, I have found myself invigorated and look forward to the challenge of active learning.

The reality of today's higher education in the United States is that students do not seem to be as interested in learning as they once were. By employing active learning strategies, students not only learn content, but process as well. This makes them better students in later courses, and better professionals after finishing their degree.

7. Acknowledgments

I would like to thank the participants of the Third Eurographics Workshop on Graphics and Visualization Education (Maastricht, August 28-29, 1995) for their comments on an earlier version of this paper.

References

[1] Charles C. Bonwell and James A. Eison. Active Learning: Creating Excitement in the Classroom. ASHE ERIC Higher Education Report No. 1, Washington, D.C.: The George Washington University, School of Education & Human Development, 1991.

[2] Frank J. Dinan and Valerie A. Frydrychowski, "A Team Learning Method for Organic Chemistry," Journal of Chemical Education, Vol. 72, pp. 429-431, May, 1995.

[3] Susan Brown Feichtner and Elaine Actis Davis. "Why Some Groups Fail: a survey of students' experiences with learning groups." Organizational Behavioral Teaching Review, Vol. 9, pp. 58-73, 1985.

[4] Jeffrey J. McConnell, "Active Learning and Group Work in a Theory of Computation Course," submitted to the 27th SIGSCE Symposium on Computer Science Education.

[5] G. Scott Owen, "HyperGraph - A Hypermedia System for Computer Graphics Education." In Interactive Learning Through Visualization, S. Cunningham, and R. J. Hubbold (eds), Springer-Verlag, Berlin, 1992.

[6] M.B. Rowe, "Using Wait Time to Stimulate Inquiry." In Questions, Questioning Techniques and Effective Teaching, W.W. Wilen (ed), National Education Association, Washington, DC., 1987.

[7] Dino Schweitzer, "Designing Interactive Visualization Tools for the Graphics Classroom." In the Proceedings of the Twenty-third SIGCSE Technical Symposium on Computer Science Education, Kansas City, Missouri, March 5-6, 1992, pp. 299-303.

[8] John Stuart, and R. J. Rutherford, "Medical Student Concentration During Lectures." The Lancet, Vol. 2, pp. 514-516, September 1978.