Teachers get paid to reach as many children as possible. Each kid is different, and how you get in their mind, how you reach their mind is kind of . . . So we try a variety of different things with the class to try to get that point across.
Some kids can pick it up from reading.
Some kids need to see a demonstration, need to see the phenomenon. Some kids need to work with it, with their hands. But they can pick it up. So you have to cajole them. If they see that you like the subject, they see you have a good sense of humor, and you can get them to warm up to you as a person.