The Student Hand Raise is a Pro feature you can use with Private Rooms that allows you to see which students need help with an activity. You can also do this to get the attention of a single student.
Make sure you "Enable Hand Raise" in your student roster. To do this click on the Roster icon on the far right. Then make sure Enable Hand Raise is checked.
From the student perspective, students can raise their hand by clicking their name in the app and clicking "raise hand."
Once raised, you will be able to see who raised their hand in the student roster.
You can lower a student's hand by clicking on the hand next to their name or the student can do so themselves from their account.