I'd think of it a bit like, teaching mathematics, so, provide examples, walk them through them, basically show them how to think in a Dialectical and Historical Materialist way, and encourage them to practice using it to better understand reality, and maybe throw in bits about history, philosophy, political economy ETC. You could give them some books to read (at their level) and then provide encouragement, maybe they get a special treat if they can demonstrate they understand the books content, and if you talk about such regularly at, you might encourage them to want to know more on their own so they can discus at a higher level with you, or even to show off what they've learned or something, what ever keeps them learning.

Edit: "regularly at home"