Did you know that pop-up books rely on science (more specifically physics) in order to work? 

They rely on simple mechanisms called levers, sliders and box folds in order to work.  The books don't move on their own though, they need the reader to give an 'input force', which might be pulling a lever or opening the page, in order to see the pup-ups move.  This subsequent movement is known as the 'output force'.

Whilst designers definitely have to think about the colours and images within a book, they also need to know how these mechanisms work in order to make a successful pop-up book!