Improving automatic code assessment

In Fall Semester 2012 we started using an automatic code assessment system named CodeAssessor to grade students' coding problems on exams. This paper describes some of the lessons we have learned in using automatic code assessment and the improvements to CodeAssessor we have made as a result of them. The students' results on the exams have improved from a median of 8/25 on the first exam given in Fall Semester 2012 to a median of 19/25 on the first exam given in Spring Semester 2013.