Spot the difference with a 4-year-old: how to play it well
Spot-the-difference looks like a quiet puzzle, but for a young child it is a workout: look at one picture, hold it in mind, look at the other, compare. That back-and-forth is the whole point, so a few habits make it go better.
Start with big, bold changes
A red ball that turned blue, a hat that disappeared. Two or three changes are plenty for a first go. Small details — a tongue, a window — come later, once the child knows what "different" means here.
Say it out loud
Ask "what changed?" rather than "where is it?". Naming the change ("the dog has no collar!") turns looking into language, and it tells you what the child actually noticed.
Scan together, in order
When a child gets stuck, don't point. Instead sweep the picture together: "let's look at the sky… now the house… now the ground." That is the strategy they will use alone next time.
Stop while it's still fun
One or two scenes is a good session at four. The puzzle will still be there tomorrow, and so will the wish to find the last one.