Depending on the age of your users, you'll want to be very careful not to run afoul of COPPA. That can be a very costly mistake.
Ways to monetize include:
1) Ads. This is likely only going to be a big source of revenue in two scenarios. The first is if you have a large audience (which it sounds like you won't). The second is if there are specific advertisers and products that would pay a lot to market to your niche audience. I don't know enough about unschooling to assess that.
You can start out with something like AdSense. If you have a large enough audience or do direct deals with advertisers, you can then plug that into DFP or something similar. You can also access more programmatic demand there as well (again, probably only useful if you have a big audience).
Depending on how much you want to risk annoying your users, you can also look into instream ads or other auto-play video content with ads on it.
2) Lead generation. Again, you have to be careful about children's privacy, but there may be companies that would pay a good fee per lead/signup/install to get your audience to do or buy things. You can check out sites like Affiliate by Conversant (formerly Commission Junction) to see the affiliate programs and pay-per-lead offers out there. And I should say that I do not know if affiliate deals often target teens (my work in that space was all over-18 oriented).
3) Subscriptions/Premium Content. If your site is useful enough, then perhaps students or their parents would pay a subscription to use it. Similarly, you can try the combo of a free, possibly ad-supported site with a premium option that unlocks more features and content and turns off ads.
My suggestion would be to focus on building out your site first and see what kind of audience you have before worrying about monetizing it. If you make something worthwhile and it gains traction, money will probably follow.