How to Train Your Dragon: Problem, Symptom; Solution, Reaction

This morning I finished a four-day EFL winter camp at a local junior high school. Each day of the camp, we watched part of How to Train Your Dragon, a movie I love. The first three days, I played a few minutes, asked the class to summarize the action, played a few more minutes, asked for a summary, and so on. It wasn't a hit. Today I played the last two thirds of the movie non-stop after warning the class that I expected them to tell me the whole story once the movie ended.