Extra credit may also be used as a way to allow a student to improve their grade after a weak performance earlier in a course.
In both of these cases, extra credit can promote differentiated instruction by factoring in optional work in the assessment of student performance.
Points might be added to an existing activity, for example, if the student correctly answers a more difficult portion of a test that would be required to meet the objectives of a unit.
Author Julia G. Thompson refers to extra credit as "a controversial topic for teachers.
"[2] In California, during late 2006, there was controversy when students were offered extra credits simply for buying course books in an effort to overcome a lack of resources.