Networking fundamentals training developed and delivered by Juniper Networks. Note students must make an account to use the resource.

https://learningportal.juniper.net/juniper/user_activity_info.aspx?id=769

Games to learn cybersecurity fundamentals. Free online games 

https://www.helpsystems.com/blog/break-time-6-cybersecurity-games-youll-love

An academic year competition that can be done with teams from schools or students can sign up individually on teams. Costs are $1000 for school teams and $200-250 for individuals. Materials and scenarios focus on Open Source Intelligence, Log Analysis, Network Traffic Analysis, Cryptography, Scanning, Forensics, Password Cracking, Enumeration and Exploitation, and Web Application Security.

https://wecyberup.org/inspire-youth/