Kids want to have fun while they learn. As a fifteen year old, I'm sure this can be by building interesting projects that has to do with characters they identify it - maybe like a website with pictures of them and describing who they are. (HTML, CSS)

After some of that, you can move on to JS where they'll actually understand programming logic. I built a site to teach people to code the web. Maybe it'll help you a bit: https://enlight.ml