When I was a child we got taught that at school. They had a large model of the human mouth and an oversized toothbrush. Perhaps that's too low tech for folks nowadays, I don't know.

Apart from the I go to the dentist 2-3 times a year, they do a great job telling me what area of my mouth I need to focus on. A toothbrush wouldn't really be able to give me that info anyway.