What services for advertising with mandatory viewing of video ads are there or how to monetize an educational site?

Question

contextual advertising

I am currently developing a site similar to znanija com with answers to the educational site of Kazakhstan, almost finished, I want to embed a mandatory video ad there before seeing the answers like on znanija com, what services are there for this? Or if there are better ways to monetize an educational site, please enlighten me. It doesn't care about ad content.

Answer 1

Just stick an ad for any popular online toy =)