This lesson incorporates computer science with an interesting enrichment topic for Environmental Science II, Astronomy - Dark Matter.  Students will be able to visualize WHY scientists believe that 85% of matter in our universe is not the same as what we are made of.  Using simple orbital speed kits, your class can combine their data and analyze it to see what happens to orbital speed with increasing distance from the barycenter of a galaxy.  They can add mass to the center to represent dark matter and see how that increases the orbital speed - just like what Vera Rubin discovered in the 1960s.