I'm an adult learner who started using Khan Academy to learn math and now physics after I retired in mid-2017. I hope to do more traveling now that I'm retired. I have a personal challenge to use Khan Academy in as many U.S. states as possible. I have managed to use Khan Academy in 10 states so far. I'm listing them geographically from northeast to southwest, although this is not the sequence in which I have used Khan Academy (although the last one I'll be listing is the most recent one so far):

Maine

Massachusetts

New York

New Jersey

Pennsylvania (my home state, although I have traveled within this state in this time period)

Maryland

Virginia

Florida

Tennessee (during a layover in the Nashville Airport!)

California