[msft] Fair points jsjohnst. I don't have a good solution for you. Perhaps the teacher can setup one Microsoft account (eg school.outlook.com) and multiple ppl can use it? (but that comes w issues too sadly).
Perhaps www.code.org is a better offering?
Also, how many middle school and high schools (especially title 1 schools) do you know have office365 for the teachers, let alone for each and every student?
Please don't regard this reply as being critical of the offering, it's certainly not and I applaud what you're doing, I'm more responding to the person who couldn't understand why login was a barrier.