Big news, Google Classroom is now open to individuals without G Suite for Education accounts! From the Google blog:
Starting today, these new Classroom users will be able to join existing classes and over the coming weeks, they’ll have the ability to create their own classes as well. Schools interested in using Google Classroom should still sign up for G Suite for Education.
This update gives schools more flexibility in how they collaborate with other organizations and students: For example, student teachers or visiting students can now easily integrate into their host school or university’s Classroom set-up.