If you're a parent I'm sure you're well aware that young children can ask the 'Why' question up to 300 times a day... ?


So I'm spending some time with my 4yo niece at the weekend and relieving some of the 'Why? Why? Why?' constant line of questioning strain from her parents. She's just come into possession of a Slinky toy and was asking why (surprise!) it walks down the stairs in the way that it does.


Now telling her all about longitudinal compression waves, kinetic energy, momentum and gravity is just going to go over the top of her head and I don't want to respond with that all time classic default reply "It just does..." . I've told her that I'll 'ask my Engineer friends' (she knows all about you and that Engineers are very clever ?) and I know that she has the memory of an Elephant and will remind me next time I visit... ?


So.... How can I explain how a Slinky works in a way that a four year old would understand?