Ask HN: How to entice HS/College students to try app?

I have created version 1.0 of a group chat app which provides value for high school and college students. It’s a better mouse trap (yes yet another group chat app). But as we all know distribution is key.

How would you go about getting groups of 20+ or more students at the same high school to download and try? Ideally for free but would be willing to pay a few hundred for first couple batches. Problem is I work full time so can’t go to campus during the day and not in that age range any more (insert Steve Buscemi meme). How have people approached this problem?