This is a really neat site made by Raytheon for STEM teachers/students. It has some of the best educational games I have seen. The games are “real world,” thoughtful, easy to navigate, and cute. I signed up as a 6th grade girl and ended up playing a math puzzle about re-arranging clothing racks in a store and a “Jewel adding game.” For physics, there was a really neat roller coaster simulation that was almost the educational version of Roller Coaster Tycoon (an outstanding computer game). The site is quite huge so I only skimmed the surface.
Here is a screen shot of the rollercoaster builder: