Here, I've set up a Use of English assignment, where the student receives a PDF of the Use of English activity and a Google doc to enter their answers on.
1) On the classwork page, the student opens the assignment by clicking on the assignment.
2) They then open the materials and do the activity.
3) The student enters their answers on the Google Doc.
4) In the top right-hand corner, they click "Turn in" to hand it in.
5) This takes them to the assignment and the 'Hand in' dialogue will pop up.
6) They click 'Hand in'.