I think a great junior program would just be a "how does content get to your phone" -- A lot of folks don't know about datacenters and networks! And showing lots of pictures and diagrams about what datacenters and networking gear looks like. You can then introduce basic routing protocols, BGP, peering, transit, last mile networks, and so on.
I am biased because I gave a (adult SRE focused) talk on this some years back
https://www.youtube.com/watch?v=KPEZU_Uk-vM and it was really well received and a lot of folks came up to me asking questions about networks.