Sketches done in school - Heads practice

I was throwing away my notes from the past year. Very nostalgic and hard to do but along all the maths and physics I found some of the drawings I did in the class (I sometimes wonder how I manage to learn and draw at the same time but it works). So here are some of them.

I did this in the chemistry class. It was funny since the teacher was trying really hard to catch me off gourd with a question so he can tell me to stop drawing.