If you are not finding appointment slots in the new Google Calendar it is because you’re on the wrong view… or you are in your Gmail. I created the slots of time on the calendar that I was available and the students clicked on the link and chose the spot that worked for them. I used Google Calendar Appointment slots to meet with students to review their student portfolios. In other words, instead of YOU manually adding each appointment to the calendar, people do it themselves. Appointment slots allow you to create available slots of people to sign up. So good news, appointment slots are still there for G Suite for Education users. It’s mostly just a new look not a loss of features.
I’m really digging the new layout for Google Calendar. Make Appointment Slots in Google Calendar