This came across my Facebook feed and if I still taught 4th grade I would definitely be signing up. Apparently Mattel has a Speedometry set for free for 4th grade teachers that helps to teach math and science skills using hot wheels. What?!?! How awesome is that?!?! The set includes lesson plans to help teachers integrate hot wheels into the curriculum.
If you are interested you can sign up for your free kit here - http://www.hotwheels.com/en-us/speedometry.html.