I do teach web development/security on a regular basis and in my classes I use Fiddler classic, and that works great. (teaching developers at companies, not school/university)
But I wish there was a student/training edition of Fiddler Everywhere, that I as a teacher could install on my student machines and that does NOT require any signup/account creation. Perhaps limited to be used for a few days before nagging for signup?
In my training typically provide a disposable virtual machine for my students and as a trainer, I do prioritize the ease of deployment/setup.