One of the kindergarten readiness checklist items is that children can work and play by themselves for a short period of time. Younger ages require more supervision and some activities need more help. Puzzles are a toy that are fairly safe and that kids can do by themselves after showing them how the pieces work. Age two and up can handle simple wooden puzzles with cut-out spaces for a couple of items. (Make sure the pieces aren’t swallowing hazards.) Three and up can do 
puzzles with several pieces or more. Here’s a set for all 4 seasons.
Puzzles use lots of thinking and problem-solving skills. When first doing a puzzle, talk outloud to yourself so children can hear your thinking process! “Oops, this piece doesn’t fit. I need to turn it and try it again. What’s next? This space is round. This piece has corners. I need to find a round piece.” When your child is working on the puzzle ask questions. “Check out that color. Does that color match this one beside it? Does this space look big enough for that piece?”Soon, your child will start to use those same figuring-out skills independently. These problem-solving tasks really grow brains! Adult ones, too; do you do those 1000 -piece puzzles?