The goal is to give reference points for the jumerical scale so the numbers can be more meaningfully compared, not necessarily to have a detailed reference that will annoy some people (too much to read) and confuse others (don't fit in).

I was thinking of something intermediate, like "took specialized classes, not 101", but I'm afraid being too specific about education means people will not take into account other things like how much they forgot or how much they learnt in the meantime. Someone who took econ 101 but works in a bank and argues about economic policy on the internet everyday and read a few good books is probably more knowledgeale than someone who majored in economics and then said "screw it all" and became an actor.

(agreed, and the question should probably be formulated to distinguish deliberate exercise from things like cycling to work)

I prefer asking for the times of exercise per week and a question for when the person last exercised to check whether certain people overestimate the amount they exercise. It would be interesting to see whether people who are better calibrated on the calibration question do better at this task then people who aren't calibrated.

I also don't think that minutes are very meaningful. Intensity matters as well. It's easier to stay with the simple question for the amount of exercise. I don't think there a strong systematic bias at play.