You can't just put a bunch of LEGO in front of students and expect them to have fun, behave, and learn all at the same time. And make sure you have a clear learning objective and set up and clean up in 45 minutes or less.
I've been doing it for a few years now and have some ideas that might work for your students, too. In this session, I plan to demonstrate how I maintain behavior and engage all of my K-3rd grade students in building based on "fairytale problems". We all know the Three Little Pigs needed stronger homes. Let's have the students show us what they can think of!