Plot: 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