It's great that you're raising money
There are lots of classic fundraising ideas but it's hard to think of ones which haven't been mentioned already...
You could be sponsored for just about anything...running, cycling, silence, wearing pyjamas all day and going about your usual business, bathing in custard, golden syrup or tomato sauce! Bake sales where you get as many people to bake things and sell them, sales of all kinds of old things, organised games or races.
And then there's the classic standing outside in the street with a tin and a big banner
Raffles are also an option, or you could make T-shirts/ badges and sell them.
Arrange a charity themed party with an entrance fee.
Overall you could raise quite a lot of money by doing all of these things, good luck!