Step 1: Tap the link that your teacher has provided.

Example:

Step 2: Tap "Allow"  to allow the Camera and Microphone.

Step 3: If you are not already logged into a Google account you will be prompted to type your name.  Then Tap “Ask to Join.”

Step 4: Wait for your teacher to accept your connection

You're in! 

At the bottom of the window you will see controls to Mute Audio, Disconnect, and Mute Video