Hey Harrison, very interesting project you are working on and I hope it becomes a success! I love the idea of getting high schoolers to think more altruistically!
I understand your stated explanation for only selecting private high schools, but have you thought of later expanding to charter or magnet high schools?
From EA forums and in-person meetups, I fear EA is already, and further going into, a kind of echo chamber due to it’s demographic of wealthy, elite, intellectual circles. Your project can be a great way to expand EA’s demographic.
The Harvard economist Roland Fryer has done similar research and projects, but instead money was used to successfully incentivize underrepresented students to academically succeed in charter and public schools. I would suggest checking out his work.
Best of luck on your project!