High school prom contract

Okay so I was contacted by a school employee to take portraits of prom attendees in front of a backdrop once they arrive to the dance. It’s a small school, will only take about an hour, and we’ve agreed on a price. My questions is, what should my contract look like? I need to get a blanket approval to photograph each student since they are minors, and to also be able to use their pictures for my own advertisements. I don’t normally do events let alone one for a school so I’m unsure what this needs to look like to cover all bases. Thanks In advance for your help!