Firstly I think we should do a sponsored run or triathlon. Everyone in year five could compete with 2 or 3 people sponsoring them, overall this could make a good profit. Other people could compete as well as year five which would make an even bigger profit.

Another idea is dress up day. This has the same plot, where people sponsor you for every different colour that you're wearing.

These are some simple ideas which could make a reasonable amount of money and be fun at the same time.