I know I have kids in class that are polite and quiet and pay attention (or look like they do) in class, and attempt the homework, and yet are just not getting it. They don't come in for help. They don't ask questions in class. It's easy for them to just not be actively involved in the learning in class and coast and "pass" (though maybe not on tests).
I have various strategies when students answer questions in class to get everyone to participate: talk to someone next to you quietly about ..., help someone or have someone help you with ..., give me a thumb vote on the answer to ..., write down your answer to ____ and I'll walk around and check.
But as I'm walking around or waiting for them to talk to each other or ask questions, there are still kids "fake" doing it. So I debate whether to call them on it or not. I don't think I can do this every time and reach every student because the lesson has to go on and that seems like it would take too much time and maybe have a negative effect. Students can just look busy or look like they're working, and maybe they are, but they're not done by the time most others are done with the current task.
Today I was starting the calculus class, and we were going over homework on the "1st derivative test" to identify maxes and mins. I asked the class as a whole, what were the steps of doing the "test". The usual suspects started to answer, and I stopped them and did something I hardly ever do. I picked on a random student by name. "I don't know". I picked on another (making sure not to pick the kids that got it). "I don't know". So I stopped class and said, "look over your notes from last class, and I'll pick on random people to answer various questions about this topic". Well. That got the motivation up. Everyone was looking through their notes and discussing things with their neighbors and one student was so excited, "I GET it, it's this and this and this". Then I picked by name random students to answer the remaining questions.
I don't do that enough. I've gotten set in my ways and rely on the strategies I mentioned way above, thinking that everyone would get a chance to discuss and learn things before someone called out the answer, and I failed to notice that there are kids not participating too many times, and that it was easy to just sit and vegetate.