Preparing for Lower Sixth Physics #9: Newton's Third Law

I did the water rocket today with three classes. The record stands at 93 metres. That's what you've got to beat next year. Anyway, it's an excuse to introduce Newton's Laws of Motion. There are three of them and you really need to know which is which. I'm going to work backwards and start with the Third Law. I learned it as "To every action, there is an equal and opposite reaction". In other words, we are talking about two different forces and they act on two different objects. Actually, that isn't clear in the statement I learned, so it has been rewritten as "If object A exerts a force on object B, then object B exerts a force on object A that is equal in size, acts in the opposite direction and is the same type." Applied here, the extra air pressure caused by pumping means that the bottle pushes the water down (the action). Thus the water pushes the bottle up (the reaction). Simples.