What things could i sell at school?

I take business studies and we have to start up our own business's inside the school i want to be a sole trader and start a franchise but what type of things could i sell our teachers giving us all �10 to start up our business's with but i have another �20. i cant do sweets or drinks because someone else is already doing that.I am a girl but i want stuff that will make me money and get me an A* in business studies any ideas?? Im 14.(no rude stuff)