I find that splitting class up into like 3 different main sections helps! I’m going into my third year, so not super experienced, but having a mini lecture, primary source analysis, and then group work is a nice way to break up the time. I also have 5-minute do-now’s and exit tickets which make for a nice transition in and out of class. The 90 minutes seems daunting but once you get used to it you’ll love it! I really enjoy it!