Hi Samuel, I just tested your app and the idea is really great!
IMO, if you really want to display ads, I strongly recommend to not make it in an intrusive way
To achieve this, I only recommend Banner and Interstitial ad types
Some tips
Never display ads on the user first interaction. This creates a bad impression of the app, so I recommend hiding Banners and not showing Interstitial for the first 1-5 launches
There’s a high chance for the app to be uninstalled if the user finds ads at the very first moment
Place banners at the bottom of the screen, or somewhere between the content where doesn’t nag and interrupt the experience (never between an article)
For your app, I would place a Banner in the first screen at the bottom, and show it only after the app has been launched at least 3 times
Interstitials are the most intrusive ones, but the ones which generates more revenue. Due to this, it is recommended to place them in a wise manner, so it doesn’t annoy users
For your app, as it’s a simple one, I would discard this option as there are not a lot of places to really make them appear
Next, regarding the ads content, go for Games
Your targeting users are students mainly, so they are interested in Games probably
Thank you very much for your answer Diego, I plan to include online exams to the app (google form), when the student has finished answering the test, the idea is that an ad appears, and until I see it or click on it, I can See the solutions.
You cannot force your users to interact with ADs. However, you could accomplish what you want to do, by using a Rewarded Ad. Here the reward would be the solution.