Mini catapult... this could be something really fun to make for a lesson that is a collaboration with a history class. Students could make this one, then take what they learned to design a different one! This definitely promotes students' skills in analyzing, problem-solving, and collaboration with each other!
Pendulum Painting. This would be a great science based lesson for EOY. This was always one of my favorite projects in middle school and I still have all my "drawings" now. Great way to tie a lesson in with this and very inexpensive. - Heart-2-Home
Inquiry Engineering Lab: from STEMmom.org provides an entire lesson plan and group of activities for learning about wind power. Learn more about this energy source while creating at-home wind turbines out of a collection of household items.