New students can be added to your roster at any time, just keep in mind that there's a maximum of 50 students per room for the Essentials plan and 300 students per room for the Pro plan.
Click on Rooms, then find the room you'd like to add additional students to, and click on the Roster menu.
Select Add One Student to quickly add their name and student ID
Select Add Multiple Students to add several students quickly - the maximum number of students you can add will be shown depending on how many students are already in the room (up to a total of 200).
For either option, enter the student's last name, first name, and student ID.
You can also choose to remove any additional rows if you change your mind. Once done, click Save.
Whether you're trying to add or edit a roster, if you have an activity running in the room, you won't be able to add/edit a roster. You'll see the error message below:
To finish an activity, go to the Results tab in your account and click the Finish button. Check out this guide to help you on how to end an activity.