What a 555 timer does in layman's terms / simple universal timer

Hi folks,

I'm helping my daughter make the universal timer kit linked below. She needs to be able to explain a bit about how it works. Everything I've found on the 555 timer is very complicated - we don't need how it ACTUALLY works as such, more a simple analogy.

Something like that 'the circuits inside the chip switch on and off so that it outputs a pulse of power. controlling how much current goes into the timer regulates how fast it creates a pulse. This pulse gradually charges the capacitor. When it's full, it discharges and activates the buzzer.'

Well that's the best I can do at this hour of the morning anyway! If someone could correct and add detail to this it would be very helpful!

thanks

Helen

http://www.jaycar.com.au/productView.asp?ID=KJ8108&keywords=universal+timer&form=KEYWORD