That looks very cool! One piece of feedback if I may: I tried the section for “similar triangles” and I got through a few questions (love the content), but then it ends like this:

> So, the two quadrilaterals are not similar. Similarly, you may note that in the two quadrilaterals (a square and a rhombus) of Fig, corresponding sides are in the same ratio, but their corresponding angles are not equal. Again, the two polygons (quadrilaterals) are not similar.

With no button to move forward, and no obvious conclusion text. At the bottom it says “1 of 3”. I’m not sure of there should have been some button letting me continue or if I’m supposed to press the menu button and just go to a different section because I’m done.

Hope this feedback is useful. The site looks great otherwise, and explained very clearly!