To find the total number of students who participated in the survey, you can either look at the "Total" row or the "Total" column in the given table.
From the information provided, the total for seventh graders is 263, and the total for eighth graders is 275. Therefore, the overall total number of students is:
263 (seventh graders) + 275 (eighth graders) = 538.
So the answer is:
538.