PTO Today

I'm planning our first movie night for my son's elementary school. The school has 500 kids and I'm trying to estimate how many drinks to buy. We're going to do cups with large containers of juice and water. Any ideas?

we have about 350 students. we only sell bottled water, popcorn and small bags of chips. We only buy a box of 50 for the chips. We buy about 150 bottles of water and we make our popcorn. We bought more chips the first time and had way too much left over. So now we stick to 1 box and we sell out. Good luck!