Schools have different policies regarding the celebration of birthday parties. I know of one school that discourages the holding of birthday parties anywhere on campus. This is to avoid discriminating those who do not have the resources to host a birthday party.
Having the party at school may prove to be more economical for you only prepare for the number of classmates your kid has. You may order the food from any food outlets or you may prepare the food yourself which does not need to be that lavish. Here's a list of food kids will surely appreciate at parties:
1. spaghetti (may be messy but kids love this)
2. chicken joy
4. hotdogs on sticks
5. cakes, candies
6. tocino on sticks
7. colored sandwiches
Question: Is there a need to prepare invitation cards if the party is to be held in school? Of course, simple handmade cards will do or if you have some extra, you can buy them by the dozen at any department store.