Data based on 8 reviews.
Pay attention and listen
Sit in the front on your phone, he values hard work. Make sure to drink all the bromothymol you receive (especially the green one). Your lab marks will thank you.
Chem 20 IB with Johnson will be something you remember throughout your high school life. While he does teach the material his lessons are filled with super cool things facts and trivia, like if you ever want to murder someone use a shotgun and use lye to dissolve the body, I don't think that would of learned these things anywhere else. Other than this, the actual material is fairly simple if you can keep up with the homework, but without that, you might be out of luck since he does expect you to know your stuff. I would focus on going to him after class if you have any questions since he stays there super late and is very open to help you with any questions you have, but I don't think you will need that. His tests have a lot of practical things so reviewing notes before quizzes and tests will help you out.