Here is the full list of all 15 Nancy Drew: Warnings at Waverly Academy achievements.
Haunted the halls after hours
Solved the case as a Senior Detective
When being a good student just isn't enough
Solved the case as a Junior Detective
Found an Easter Egg
Challenged Leela a lot
For working the snack shop more than most
Obtained and held the high score in Double Take
Searched for that perfect book
Be an avid photographer
Knock, Knock. Who's there? You!
Tickled the ivories over and over
Investigate the source of every rumor
Break more than a few rules
You correctly answered the Trivia question