Show a student their score compared to others' scores

This is not possible via the inbuilt functionality. You'll need to store the results of all the students at some other place and then retrieve them, most probably using a webservice or JS.
Search the forum for uploading to results to Google Drive, you can use that to accomplish this task.

Hi, magdalenaiwanowa -- this may be a different approach than what you are thinking, but you could create a summary report with mean scores, percentiles, and other anonymized data that would put each respondent's scores in context without compromising privacy. You could provide a link in your thank you message to a resource that would be a "thank you" for participating in the survey.