Are You Smarter Than A 5th Grader?

In order to unlock this achievement you'll have to use all three available cheats in one playthrough. This can be done in both "Exam", and "Study" mode. When the credits roll after each playthrough this is where you'll see the award for "Reference Checker" if you did it correctly.

I found it easiest to combine this achievement with the Graduated achievement by playing "Study" mode with eight players, and always having one player use all three cheats. I'd like to also mention that there were times when I'd have more than one player use all three cheats, and I would not get the "Reference Checker" award during the credits.

Another way to grind this achievement out is to play "Exam" mode, and use the three cheats to answer the first three questions correctly. Then during the second question of 2nd grade you can get that question wrong, and "Reference Checker" will always pop up as an award during the credits.