This achievement is earned for finding optional photo #10. If missed on the first run, you can "Play Episodes" and select specific parts of the Episode in order to find the missing optional photos through
collectibles mode. The following collectible is described and can be seen below:
[
7:42] - Optional Photo #10
Walk into Mr. Jefferson's class and take a picture of Alyssa in front of the window.
Collecting all 10 photos will also reward you with the following achievement: