If you've got older kids, you won't want to miss this temporary exhibit (through Sept. 1). In our preview, we compared the human centrifuge to a scaled-down Gravitron. But really it's more similar to the Gravitron's carnival cousin, the teacup ride. Kids will love testing the concepts of spin while mom gets a great arm workout. And there are lots of other fun twists to try, from the racing rollers to the air thrusters, and even a cool spinning chair.