You can add students to a Google Classroom by sending an email or by sharing an invite link or class code.

Google Classroom provides a system for teachers to create, share, and grade classwork and for students to access and complete assignments. Classroom works with other G Suite applications, such as ...

“Today, we’re introducing new coursework endpoints, which allows developers to access assignments, grades, and workflow,” Google Classroom software engineer Ed Kupershlak wrote in a blog post.