Overview: Dr Chris and Dr Xand reveal how your brain enables you to learn new things with the help of three human "samples" from the Cupboard-of-Everything, a giant pile of sand and some water! In Operation Takeover, the twins join the fire service and discover how tough it is to rescue people in a fire. Dr Chris heads to the ophthalmology department to find out how to treat a lazy eye, and we catch up with Ouch Patients Bolu and Millie. Meanwhile, in accident and emergency, one patient has dislocated her ankle and another has injured his knee in the playground.