Teaching HTTP? Have students pass paper notes through a 'server' student who only answers correctly formatted requests.
Nobody forgets their first 400 after that.

Teaching HTTP? Have students pass paper notes through a 'server' student who only answers correctly formatted requests.
Nobody forgets their first 400 after that.
Teaching Git branching? Skip the diagram. Have students role-play editing a document with sticky notes, then merge by hand. Conflicts stop being scary once you've resolved one physically.