score:2
A tourist visa enables you to come and visit whenever you like. At the port of entry you will get the 6 month visa usually enabling you to stay in the country for 6 months at a stretch. I checked out coursehero, it would depend on the course you are taking but courses there seem to be adhoc and open for all to sign up. Thus they may not need the visa requirement (Unsure how will they check that requirement) If they allowed you to sign up without the requirement then does not seem to me that they would need a student visa just for that.
Your best bet is contacting the course folks directly rather than coursehero.