Loved it! I didn't quite get the significance at first, but then it dawned on me when I got to the visual acuity part.

The problem of measuring smaller and smaller things is one of the constant and most important problems in science.

One thing I missed, is there a key formula that is worth remembering here?

My user test: https://www.youtube.com/watch?v=M6HJ6KDWxGA&list=PLnN2hBdpEL...