Whoever had the object first gets three confirmed minutes with it, timed visibly on a phone or kitchen timer. Then it switches to the other child for the same duration. Both children can see the countdown. The timer is the authority — not the parent, not whoever argued loudest or longest — and that impersonality is what makes the rule hold.

What you need

Timer (phone)

How to do it

1"Decide fast who had it first. Don't investigate — just call it. Three minutes. Timer starts now. Show them both the screen."
2When it goes off, the object switches. No appeal.
3Step away. The timer is the authority now, not you.

Variations

Korb-Tür: If they argue about who had it first, say once: "I'm deciding: you start." Then set the timer. No renegotiation.
Ausstieg: After both have had their turns, put the object away immediately. Don't ask if they want another round. The timer ending is the end of the activity.

💡 Parent tip

Don't use 'fair' as the criterion. 'Who had it first' is a workable rule; 'fairness' is a debate. Children can contest fairness indefinitely. First-possession is harder to dispute.

What your child develops

Turn-taking under structure — a visible countdown makes the wait concrete and finite rather than indefinite
Impersonal authority — a timer is fairer-feeling than a parent because it can't be accused of favouritism
Delayed gratification — waiting for a known, timed duration builds tolerance for frustration