Once you're done Editing the assignment and shared the Class Code with students, you will have the ability to interact with the students and give feedback.
To do this, click on the "View Work" tab.
In the screenshot below, I can see that a student named John is currently working on the assignment. When a student is logged into the assignment, the slide they are working on will be bolded like the first slide below.
Check out these help center resources for more information!