Requiring vs. Recommending
For CodeLab to have a broad impact on your class, the vast majority
of students need to be actively working on the exercises on a regular basis.
Our instructors' experiences have shown that this is not possible unless
completion of CodeLab exercises is required by the instructor and counts
for a percentage of the student's final grade.
When instructors just recommend CodeLab, only a few students use it at the beginning,
then a few more after the mid-term and maybe several before the final exam.
The students who could have benefited the most will not use it, or will use it too late
in the term.
On the other hand, those instructors who have required it for a grade have
reported that there are less students dropping out, better performance on
tests and projects and fewer questions during class about "basics".
Percentage of Grade
CodeLab works best when required as 5-10% of a student's grade.
Under 5% does not provide enough motivation for the student to complete the exercises
while 10% -- the equivalent of a letter grade -- is usually a sufficiently strong incentive.
Our instructors who have required CodeLab for over 5% of the grade, have reported that the
large majority of their students complete the assigned exercises and feel their learning
has benefited from use of the system.
CodeLab exercises provide the greatest value if the student works on them
right after the pertinent concepts or programming language constructs
have been introduced in class. To encourage this,
faculty should use the CodeLab course management facility to
assign appropriate deadlines for specific groups of exercises.
CodeLab does not include any guards against plagiarism
because we feel that we don't have to.
We are not naive to the tendencies of students to take the easy way out,
it's just that, CodeLab has been designed in such a way that it's not punitive but supportive.
In our experience students recognize this and see that they can get the answer
themselves quicker by working with the system than by copying from a classmate.