Let them build!!!! Kids love to build things. It completely engages them and they have fun.
volume of a triangular prism (there is a review problem and then their choices for the day). The next day we did surface area of a triangular prism (two review problems and their choices for the day). For good work and correct answers they got marshmallows.
Oh, and apparently I say spaghetti funny. They never miss a beat.