When you arrive at the classroom, check the board. Then read The Weekly on this site. Every class. If you miss a class, check The Weekly for what you need to know and do. There is always more to learn, more projects to complete, more experimentation that can be started. We’re never done, here in the Labs.
“I didn’t know” is not an excuse. Also inexcusable are: “I’m done;” “I did everything you asked;” and “I don’t know what (else) to do.”