Brain asks the question of what it would be like living without electricity. Paralympian Sarah Storey, environmentalist Helena Marschall and a powerless Leila offer help.
Brain's question is a hot one, what if the floor really was lava. Leila tests a homemade lava-proof suit, Ken gets tips from gymnast Joe Fraser and lava-facts from Professor Chris. Show more
Brain wants to know what it would be like if we lived underwater. Zoologist Megan McCubbin and inventor Jun Kamei wade in with Leila to help.
Brain asks the question of whether you can kick a ball to France. Footballer Leah Williamson and physicist Steve Mould are on hand to help find the answer.
Ken attempts to work out what would happen if everyone in the world came round for tea. Leila works on a seating plan, and a global internet chef takes care of the cooking.
Brain has been keeping Ken up with another question: "What would happen if you never went to sleep?" Leila is wide awake, and Dr Ranj is on call to help with the sleep facts.
Ken’s had enough of Brain’s questions, but that leads to a new one: why does Ken get so annoyed? Can psychologist Leila and presenter Andy Day help find the answer?
Ken's brain wants to know if it's possible to catapult yourself to the moon. Space expert Vinita Marwaha Madill and inventor Tom Stanton have answers - but Leila may have to test it out.
Brain loves playing rock paper scissors, but hates losing - so he asks Ken to find out how you can always win. Show more
Ken's brain is searching for an answer to the question of whether we can talk with dogs. Leila knows just where to look, while Ken has help from Storm Huntley with her dog Boo.