If you transfer students into other rooms and want to record activities and messages you will want to be able to filter by "Signed-In" room to see the students currently in that classroom.
This setting is device specific, you will need to enable it on each device as needed.
Step 1: While logged into the app, click on the room filter at the top of the screen
Step 2: Scroll to the bottom of the room list to enable the "Only Signed-In Students" option (red arrow below):
Now when you select a room of students to record an activity or send a message, the students currently signed into that room will be displayed.