I would go with tasks where they get to "hack" or learn about each other. Give them usb sticks, make them put a silly trivia on an encrypted 7z with passwords that are somewhat crackable. Then, take their usbs from them, and distribute them randomly, and let them use jack the ripper or so. Twist, you would have added a virus or something into the USB stick, so they get infected with a "silly pop up" once they start jack the ripper. They get to play, and the exercise will stick with them.
Teach them about 10 minute mails pages, to open a silly account t somewhere.
Make them use a VPN like mullvad or some that you have set up to access a specific page or make web searches. They can notice the difference in content depending on the country they are exiting with. Twist: you control the VPN, provide them at the end with a list of accessed pages so they understand how the vpns do not ensure privacy. Explain simply what a VPN is (tunnel,etc).
Follow-up: teach them to learn to troubleshoot and search. Take the fear of breaking something from them by providing them with a VM with windows where they need to fix something or install a driver. Provide them with a Linux VM just for them to try too.
Teach them mistrust. Make them upload things to a copy of Google docs or something, and then show how you have access to everything.
Teach them about open source as a precondition for being able to trust software.