When a student receives notification that they submitted a correct answer for a problem, they are given a receipt of their submission. If a student claims that her data has somehow been lost, then you can easily recover this data with the receipt number. This option is mainly reassurance for the student because they can keep track of their receipts. It is also reassurance for the instructor because she can request that students keep track of receipts before contacting her with information about possible data loss.
To verify a receipt navigate to the problem under discussion and
Content grades within the Functions bar of the Inline Menu.
On the Grading screen fill in the receipt number in the text box at the bottom of the page and press
|Verify Receipt Number|