A teaching tool that measures how hard the brain is working (fastcompany.com)

> When we learn something new, [...] We could overwork ourselves and not realize it. [...] It’s only when we show up for an exam [...] that we know if all that practice actually worked.

So that's why you have to shut the book and recite the study material.

I would love this tool.

But you can do this for yourself. Meditation is the measurement, and continued focus is the goal.