Teaching a large class is different from teaching a class of moderate size in many ways. Among others, one of the difficulties is that teaching staff may not have sufficient time to give students regular assignments and monitor their progress by going through the students’ work personally. Students also suffer from the lack of timely feedback from the lecturers.

This is particularly true in our teaching of PC1431 “Physics IE” & PC1432 “Physics IIE” to as many as 1,500 first-year engineering students. To overcome this, we have adopted an online tutorial system where students are given weekly assignments to work on. Since the answers are submitted electronically and marked by the system, students can receive feedback instantaneously.

Figure 1. A sample question from WebAssign. Numbers in red
(7.00 in the example shown here) font are randomly generated.

The objectives of the online assignments are to prepare students for the week’s lecture and to encourage them to review contents covered in the previous lecture. The problems of each assignment are carefully selected and are typically related to contents covered during the week.

We have evaluated a number of online systems before selecting WebAssign. In comparison to other similar products, WebAssign has the largest database of physics problems and its cost is relatively low. The numerical values in almost all the questions are randomly generated within specified ranges, so that each student sees the same problem with different values. Therefore, different answers are expected from students. This minimises the problem of students copying answers from each other.

To encourage participation, students’ performance accounts for part of the module’s continuous assessment. As the objective of the online assignments is to enforce student learning, they are given a relatively small weightage in the module’s assessment. We have also implemented a unique scheme of awarding marks. Students are allowed to make multiple attempts for all questions. However, for each additional attempt, the mark for each question is reduced by 20% (i.e. if an answer is correct at the first attempt, students are awarded full marks for that question. If the answer is incorrect at the first attempt but is correct at the second attempt, students are awarded 80% of the marks, and so on). This is to encourage students to really think about the question before solving it, rather than attempting it by trial and error. To increase the system’s effectiveness, we added hints and suggestions for further reading to the system. These are shown if students enter wrong answers.

We have been using the system for two years. Based on our observations and student feedback, the objectives of the online assignment have been achieved. The weekly online tutorial assignment generates a lot of discussion among students, through which they gain a better understanding of the main principles. The system is popular amongst the students as it provides a means for them to confirm their answers and get instant feedback. It complements our normal small group tutorial discussions very well. We are currently working with the Centre for Instructional Technology to make more effective use of the system and to develop our own online tutorial system.