I know you asked this question 17 months ago!!!, but I only saw it today.  One project which has been well-received at Cabarrus County School is a paper airplane contest which takes places each year on the anniversary of the Wright Brothers first flight (very appropriate for a school in North Carolina where that flight is featured on our license plates).  The local Embassy Suites allows the school district to use their 10-story atrium for testing the students' designs.  The airplane which stays in the air the longest is considered the winner.   One of the very nice aspects, in my opinion, is that students from our STEM magnet high school and middle schools act as design coaches for the students from our STEM elementary schools to give them tips on how to make their airplanes more aerodynamic.  In addition to teaching the students about design and how to turn failures into success, the event also generates a lot of good publicity for the school district.