Professor McCork and Doctor Knowles ask 'How long would it take to walk the Earth? Meanwhile, the normally fearful Colin embarks on a solo Wilderness Survival Challenge. Things could get very creepy.

It's roller disco day and everybody is having lots of fun, except for Doctor Knowles who just can't quite seem to get the hang of it! The crack TV science team investigate the big question 'How many atoms are there in our bodies?'.

Knowles and McCork ask 'Why do we make saliva while we eat?' Backstage, the crew is awaits a very special guest - it's only Colin's biker mum, Janis!