If you want to help children understand why they should go there, you can also show them this movie https://fsfe.org/activities/ada-zangemann/movie (available in different languages) or read the book with them (several translations here https://hosted.weblate.org/projects/fsfe/ada-zangemann/ ) :)
I didn't want to, but now that the idea came up that FOSDEM Junior will teach children about freedom and openness: In the last years, FOSDEM Junior required registration on a hostile platform that had tons of trackers and wanted to share all sorts of information with a few hundred "partners" that "value the privacy" of the children, and some workshops required children to use an Apple or Google smartphone. Most workshops use free software, but still require registration with the hostile, commercialised platform, and openness definitely does not appear to be a priority at FOSDEM Junior. Teckids offered help, but we never heard back from FOSDEM. -nik