Go to lessons > click on the three dots on the right hand side of the lesson
Click on share > A share lesson dialog box will pop-up
Add any additional notes for the lesson, select type as assignment, set a due date if submission is required. You can choose to allow parents to download the assignment.
You can also share the lesson as a learning experience
Assignments vs Learning Experience
Once Lessons are shared with students, it converts into an assignment or Learning experience. A student is expected to complete the assignment and complete submission then. Both learning experience and assignment will show the Submission tab at parents' end. Learning experience will not have a due date whereas Assignment will have a due date.