Suppose we play the following game: you give me $100, and then we flip a coin. If you win, you get a prize of $XXX. If you lose, you get nothing. What's the smallest prize that'd convince you to take the bet? (Loss avoidance test)
What do you think of this idea for our online ACT-study site: you get to select a virtual pet (dog), and customize him / unlock new pets by spending points in a time-limited store. You earn points by answering questions correctly and completing challenges.