Under the Classwork tab, select the assignment. Click "View Assignment" and under "Your Work" on the right side, you can click on "+ Add or Create." From there, you can attach Docs or other Google App work, as well as Files. If you want to attach a photo, select Files and choose the photo that you would like to attach from your Google Drive.
Take a clear image of your work with your smartphone. Open Photos, and select the photo that you would like to upload to Classroom. Tap on the square with an arrow at the bottom of your screen, then select Classroom from the icon section (you may have to scroll to the right a bit to find it; also, you need to have the Classroom app on your phone for this to work!). Once you are in Classroom, find your class and select "Attach to assignment." Select the assignment in which you'd like to attach your photo, and VIOLA! (Don't forget to click "TURN IN" when you are done! :)
Within Classroom, click on the Classwork tab. There you will see all of the assignments for that class. To the left of each assignment is a circle icon with a clipboard. If the icon is gray, your student has turned in the assignment. (Check to make sure the work has been completed and attached too; you wouldn't want to turn in an empty assignment!)
Within Classroom, click on the 'hamburger' menu on the left. Scroll all of the way to the bottom and click on Settings. Here you can turn on/off email and mobile notifications for each Google Classroom in which you are enrolled! Getting notifications will help your students receive important announcements from their teachers! Click HERE for a video with more details!