This is a form that you can use to allow students to correct any incorrect test questions. The form is set up to allow students to earn back 30% of their questions, and is useful for students to re-visit a test and to correct their mistakes. I suggest offering a study session before letting students do test corrections.
The form is a fully editable Keynote file, but can also be opened with Powerpoint. (Some formatting may be affected by opening in ppt). I have included two versions for an example of how you could modify the form to best suit your needs.