Very nice! Wish I had this in my ancient school days.

There are 2 things that I think would make the experience more enjoyable: 1. When an element is clicked on the left side, it opens on the right side and vice versa. It'd be more pleasant if it was anchored to the element that triggered it. 2. The hover effect over open element info makes it less readable. Leaving it as is instead of changing color and popping out would be preferred.