Nina looks at different household inventions and finds out how they work. With the help of her trusty neurons she examines the items to answer children's questions. In this episode of Nina and the Neurons Go Inventing Julie, Sophie and Charlie ask Nina: How does the toilet flush? Good question! With the help of beautiful Belle, Nina gets to work to find out the answer. After they have had a good look at the flush, Nina takes the girls far out to sea to visit another great invention that uses the same science. This episode is all about floats and if you want to learn how to make your very own flush then tune in.