Create or find a classroom resource that teaches students about creating strong passwords, passcodes or passphrases.
I would play a game like 20 questions. I would have all students create their own password/code to enter a space in the classroom (for example). In pairs, students would have 10 questions to ask to try and obtain information (eg: what is your dogs name) and 10 attempts to guess the password.
For older students who may think more broadly, password duel may be a suitable activity:
https://www.sciencebuddies.org/teacher-resources/lesson-plans/password-security