You and a group of friends notice some things about your school that need changing (cafeteria menu, damaged lockers, write a letter to the principal proposing that changes be made.
*i just really need with an introduction like a few things that needs to be changed in school*
*some paragraph starting would be too really*

If it's a letter you'll need to start with the principals address and your address.

You can start it with something like : "Dear Sir, I am writing this letter to propose that some changes should be made to several different areas of the school"

You could make points that the cafeteria menu is too unhealthy or there's not enough variety, maybe it's too expensive?
You could say that the damaged lockers are a risk for the security of the pupils belongings.
Maybe also that the toilets are dirty and aren't cleaned well?
Also talk about litter?

Hope this helps!