Larsen puzzles have a frame that allows the puzzle pieces to be easily placed again and again. Each puzzle piece has a unique shape that fits only in one place within the frame. Because the total thickness of the recycled cardboard in Larsen puzzles is 4.4 mm, it will last for years. Various educational frame puzzles are available in the Larsen Educational Puzzles series. These include topics like biology, math, geography, learning to write, learning to tell the time, and more. Why Larsen? - Younger children develop their motor skills with the unique puzzle pieces. - Older children also play and learn about interesting themes. - Original themes encourage children and help them concentrate. - Extra thick and sturdy puzzle pieces. - Made in Europe from recycled cardboard.