Almost all children struggle with transitions, especially when they have to stop a preferred activity to go do something else. Sometimes, as a therapist, I intentionally do something to trigger negative feelings in a child. Not because I like to torture them, but because then the child can work through those feelings and practice using calming strategies to cope with them. This is one of those activities.
What I do is have a child start on a puzzle and tell them that they have a certain amount of time to work on it. I then explain that once the time is up I am going to tell them to put the puzzle away (whether it’s finished or not) and the expectation is they will say “Ok” and clean it up right away. No “let me put one more piece in” or a whiny “but I’m almost done!” Just an “Ok.”
Then we practice. The first few times I will warn the kiddo that their time is almost up, and remind them that they should say “Ok” and pick up right away. I also prompt them to use a calming strategy, in order to cope with any frustration they have with being directed to put the puzzle away without being able to complete it. After they can successful do the practice a few times, then I stop any reminders or prompts and let them do it on their own. As always, I provide lots of praise when they are able to accept the decision and use a calming strategy to regulate their emotions.