Mark Urban-Lurain (urban@cse.msu.edu)
Donald J. Weinshank (weinshan@cse.msu.edu)
Department of Computer Science & Engineering
Michigan State University
Designing instruction to provide "computing literacy" for non-Computer Science students is a challenge faced by computer science departments in many colleges and universities. (Joyce, 1998; Kolesar & Allan, 1995; Townsend, 1998) To meet this challenge, we conducted a series of interviews with the Chairs of 67 departments on our campus to determine the needs of their students. Some themes we identified are:
These themes led us to create a fixed course structure with continuously changing course content. The structure provides feedback for assessing students and revising the course content to meet the changing demands of client departments, changing student experience, and changing hardware and software environments.
To meet the needs of the different client departments, we designed the course with "core" materials for the first half followed by "tracks" appropriate to various majors. However, computing concepts (e.g., data representation and abstraction) provide the foundation for the diverse application content.
This paper focuses on the key component of this system: performance-based assessment. We summarize how our assessments are designed and how the data from the assessments are used to improve student learning and revise the course.
A major limitation of many introductory courses is that assessment and evaluation depend on surrogate measures, such as exams and quizzes that test static recall. To address these problems, our course:
Bridge tasks (BTs) are evaluated on a mastery pass/fail basis. If a student demonstrates mastery on the first bridge task, he or she "locks in" a minimum grade of 1.0 in the course. For each subsequent BT passed, the student's course grade is incremented by 0.5 until she or he has passed the 3.0 BT. In the strict sense, this is a modified mastery model in that students must complete the five BTs within the confines of a semester (about 12 BT attempts), rather than having an unlimited amount of time.
Once a student passes the 3.0 BT, s/he may choose a semester project to attempt increase the course grade to 3.5 or 4.0.
This assessment model
Because of large enrollments (1800 students per semester) and resource constraints (two full time faculty plus Teaching Assistants) cost-effectiveness is a major design consideration. Performance-based assessments are usually more labor-intensive to create, administer and evaluate than traditional multiple choice or computer-based-training exams (Schoenfeld, 1994). To adapt performance-based assessments to a large enrollment course and use resources most effectively we considered several factors:
Each BT consists of multiple dimensions, each of which assesses certain concepts. Within each dimension, there are multiple instances, specific tasks to test the students abilities to apply the concepts. Furthermore, each BT contains one or more extension tasks, materials not explicitly covered in the course but to which the students must apply the concepts. These extension tasks test transfer by having students apply the concepts to the solution of new problems.
Each students BT is created by randomly selecting a single instance for each dimension. For each instance, there is a detailed set of criteria used to determine mastery of that dimension. Mastery on a BT is determined by combining mandatory and optional measures of mastery on the various dimensions. The BT contents are summarized in Table 1.
| Bridge Task |
|
| 1.0 | E-mail; Web; Distributed files; Help |
| 1.5 | Boolean searches of databases; Word-processing; Creating Web pages |
| 2.0 | Hardware; Software; More Word-processing |
| 2.5 | Spreadsheets (functions, charts) |
| 3.0 Track A | Object embedding; Designing Web sites; Network communication tools |
| 3.0 Track C | Advanced spreadsheets; Importing and transforming data; Data analysis; Add-on tools |
| 3.0 Track D | Advanced spreadsheets; Fiscal analysis and modeling; Add-on tools |
This model provides a rich database of student performance that we use to
Table 2 shows two measures of the BT repeat rates for Spring 98. For each BT, the table shows the number of attempts to pass that BT. The data are presented both for the entire class and, separately, as a percentage of the students who eventually passed that BT. Since some students never pass all BTs, the Percent of Class Passing decreases on each successive BT.
For each BT, about 50% of the students pass on their first attempt, about 33% pass on the second and about 10% pass on the third.
There is no significant difference on the Percent of students who passed BT across BTs by single factor ANOVA across BTs (N=1770 students.) We therefore conclude that the BTs are of comparable difficulty.
One attempt |
Two attempts |
Three attempts |
Four or more attempts |
|||||
Bridge Task |
Percent of class passing |
Percent of students who passed BT |
Percent of class passing |
Percent of students who passed BT |
Percent of class passing |
Percent of students who passed BT |
Percent of class passing |
Percent of students who passed BT |
1.0 |
68% |
71% |
20% |
21% |
6% |
7% |
2% |
2% |
1.5 |
40% |
43% |
36% |
39% |
12% |
13% |
5% |
5% |
2.0 |
45% |
52% |
27% |
30% |
11% |
13% |
4% |
5% |
2.5 |
42% |
53% |
26% |
33% |
9% |
12% |
2% |
2% |
3.0 |
28% |
46% |
24% |
40% |
9% |
14% |
0% |
0% |
Table 3 shows the final course grade distribution from Spring 98 in tabular form. Grades of 3.5 and 4.0 are obtained by doing a semester project only upon successful completion of the 3.0 BT.
| Final Grade | 0.0 |
1.0 |
1.5 |
2.0 |
2.5 |
3.0 |
3.5 |
4.0 |
| Percent of students | 1.5% |
3.9% |
4.2% |
9.3% |
18.0% |
19.5% |
13.8% |
29.9% |
To those accustomed to a normal distribution, these results may be startling. However, as Bloom, Madaus and Hastings (1981) point out:
If we are effective in our instruction, the distribution of achievement should be very different from the normal curve. In fact, we may even insist that our educational efforts have been unsuccessful to the extent that the distribution of achievement approximates the normal distribution. (p. 52)
We use BT data to revise the instruction and assessment. Based on the analyses of the BT performance statistics from fall 1997 semester, we made extensive revisions of the instruction and BTs before spring 1998. While the previous data show the internal consistency of these changes, student ratings provide an external measure of these changes across semesters.
Table 4 shows some of the Student Instructional Rating System (SIRS) data for the first two semesters we offered this course. Students are asked to respond to each statement on a scale of 1=strongly agree, 2 = agree, 3 = neither agree or disagree, 4 = disagree, 5 = strongly disagree.
Question |
Mean Fall 97 |
Mean Spring 98 |
| I usually did my homework before coming to class. | 3.47 |
2.23 |
| I learned a lot in the group exercises in class. | 3.79 |
3.15 |
| The Bridge Tasks were a fair test of the material I learned in class. | 3.50 |
2.29 |
| I felt that the "extension tasks" on the Bridge Task, which asked me to do something I had not previously done, were reasonably connected to what I had already learned. | 3.68 |
2.32 |
| The grading was fair for the Bridge Tasks. | 4.29 |
2.98 |
| The grader's comments explained what I did wrong on the Bridge Tasks. | 3.51 |
2.55 |
| I feel that my course grade will reflect my understanding of computer concepts. | 3.88 |
2.80 |
| I would recommend this course to my friends. | 3.70 |
2.48 |
On every question, the student ratings improved dramatically. The average overall improvement is 1.13 (on a scale of 1 to 5). All results are very highly significant by two-tailed T-tests. We attribute these improvements to the extensive revisions of the course and BTs we made from fall to spring.
This course has been very well received by our client departments. As the first years cohort progresses through the University, we expect that student grades in the course will successfully predict preparedness for subsequent courses in our client departments. This will allow our client departments to concentrate on using computing technology in their domains.
These results should be of interest to educators who are