Learn a Proper Card Game
Teach them a game adults actually play.
Fold it in five minutes, then race it across the table for half an hour.
The folding is the activity. The racing afterwards is why they make six more.
Origami demands precise, sequenced folding with immediate feedback, since a sloppy crease produces a frog that will not jump. That direct link between care and result is unusually motivating.
None needed.
They fit in a pocket or a pencil case.
Teach them a game adults actually play.
A cupboard of containers and lids that do not match. Sort it out.
Fold a page into six boxes and tell a whole story inside them.
One sheet of paper, eight folds, and endless silly predictions.
Reach in, feel one object, and describe it without naming it.
One of you thinks of something. The other has twenty yes-or-no questions.