Your teacher may invite you to a Google Hangout for live video conferencing. Check your email and respond to Hangout requests from your teachers. Familiarize yourself with responding to meeting requests in Gmail and Google Calendar.
Go to your calendar and create a meeting as normal.
Click Add rooms, location, or conferencing and select Google Hangout.
Invite your guests and send the invitation.
Here is a quick video (note, there is no audio in this video, just follow the steps):
While in Hangouts, press the 3 dots in the lower right of the screen and select Record Screen.