…actually now is somewhat backdated, cos google has since made classroom freely available to all, from Apr 26, 2017 onwards, as noted in this blog post (:
in other words, anyone with a personal google account can use the system to start managing learning (cf. LMS). school teachers are however encouraged to use Classroom by enrolling the school in the G Suite for Education. this would allow your to more conveniently manage your classes of students.
btw, thanks to PS for first highlighting this news to us. enjoy (: