My kids are in school in NY. I wouldn't let them do a school project focused on firearms.
Ignorant PTA members would be all over it; my family would be labeled "gun nuts". It would genuinely frighten some. I hate it, but its the world I live in.
All that aside....if socially acceptable in your neck of the woods and authorized by the parental units, you can shoot various calibers into wet newspaper and compare depth of penetration/bullet expansion. Compare velocities within calibers, varying bullet weights/designs, barrel lengths used,pellet rifle vs. .22, etc. Take photos of recovered slugs. (I would NOT bring lead slugs into a school due to the toxicity of the lead itself)
Wet paper is commonly used as a poor mans ballistic gelatin to ROUGHLY compare penetration. It is inconsistent with expansion data IMO.
Collect newspapers on recycling or trash night, ask neighbors or school mates.
Soak it overnight in garbage bags, drain excess water before shooting.
If you know anyone with a digital scale borrow it; compare weight retention of recovered slugs. Should be good for an extra chart or 2
What ever you decide, PLEASE DO IT SAFELY
You can even write up a paragraph or 2 showing safety protocols you followed. Its the best way to show anti-firearm-ex-teachers your batting for the good guys. GL