When turning in an assignment through Google Classroom,...
1. Go to classroom.google.com and click Sign In. Sign in with your Google Account. ...
2. Click the Classwork button. Then, click on your assignment
3. To open the assigned file, click the thumbnail with your name on it.
4. Enter your work: Remember to select from the correct location in which your work is coming from: Google Drive, Flie, Etc.) When selecting your have file, be mindful of what you're selecting: docs, slides, etc.
5. Choose one: In the document, click Turn in and confirm.
Resource video for students to view on how to submit assignment to the turn it in box on google classroom: