Jem makes his own diamond and then proves they aren't forever. Dr Yan explains the science of popcorn, and Dallas investigates why we haven't cured cancer yet, meeting the team that hope to change that.

Jem witnesses the awesome power of rockets with the Bloodhound land speed record project, Yan re-enacts an Ancient Greek experiment to measure the earth's circumference with a couple of sticks, and Dallas goes in search of a robot to call his own.