A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data
On the summary sheet, create a list of the sheet names that you want to include in the sum.
Select the list and name it (for example) Sheets.
Let's say the student names are in A2 and down on the summary sheet.
In B2, enter the formula
=SUMPRODUCT(SUMIFS(INDIRECT("'"&Sheets&"'!C:C"), INDIRECT("'"&Sheets&"'!A:A"), A2))
Here, INDIRECT("'"&Sheets&"'!C:C") is the range to sum, and INDIRECT("'"&Sheets&"'!A:A") is the range with names (the criteria range).
You can add more criteria range / criteria pairs as needed.
Fill down.