Here is a list of the 4 projects I have had the most success with. I try to use/create projects that are fun and connect math to the world in a meaningful and interesting way.
#1. Use scientific notation to analyze human impact on the environment.
#2. Be an epidemiologist and use statistics to study a zombie outbreak!
Best for: 6th grade statistics
#3. Learn about mathematical art and create your own using geometric transformations:
Best for: 8th grade math and geometry
Inspire kids with these resources by exposing them to geometric art from around the world
Digital desmos version of the project available here.
#4. Be a fashion designer and create a graphic design using linear equations:
Best for: 8th grade math and Algebra. Could easily be modified to include more complex equations for higher level math.