Online homework system clusters similar student programs together, so instructors can identify broad trends.

online-homework

A screenshot of the OverCode user interface. The top left panel shows the number of clusters, called stacks, and the total number of solutions visualized. The next panel down in the first column shows the largest stack; the second column shows the remaining stacks. The third column shows the lines of code occurring in the cleaned solutions of the stacks together with their frequencies. (Courtesy of the researchers)

In computer-science classes, homework assignments consist of writing programs. It’s easy to create automated tests that determine whether a given program yields the right outputs to a series of inputs.

But those tests say nothing about whether the program code is clear or confusing, whether it includes unnecessary computation, and whether it meets the terms of the assignment.

Professors and teaching assistants review students’ code to try to flag obvious mistakes, but even in undergraduate lecture courses, they usually don’t have time for exhaustive analysis. And that problem is much worse in online courses, with thousands of students, each of whom might have approached a problem in a slightly different way.

In April, at the Association for Computing Machinery’s Conference on Human Factors in Computing Systems, MIT researchers will present a new system that automatically compares students’ solutions to programming assignments, lumping together those that use the same techniques.

(Next page: In-depth detail about how the system functions)


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