Instruction is more than just designing the lesson and teaching, so we give this a solid "B" because classroom management is important. It's probably be more along the lines of an A if we could meaningfully integrate content in some way, but that's really not what ClassDojo is for, and I wouldn't want to see the company screw around with a great product and make it something else if it meant getting "ask Billy a harder math question" as a button. This rating isn't an indictment of the design.
I think students that respond well to this kind of classroom management solution will love it. The only reason I ding it down to an A is that there's real room for growth for the individual kid's attached device. I love the idea that when you make a mark for a kid, you could have it sent only to that child's device, as a pop-up, so that silent reminders and notifications could be used in addition to the public display. I don't mean to be predictive in my review, but this is an obvious area of growth that'll amp the experience for kids, so we're going to leave room for improvement here.