Trucky 3

Place the puzzle pieces inside the trucks so that they don't stick out. There is only one solution, yet 48 challenges. These little trucks combine a great puzzle with a fun toy. Trucky 3 is made from sustainably-harvested, eco-friendly wood from rubber trees, and plastic.
— As of 07/20/2012 this product had 4.4 out of 5 stars from 5 reviews on Amazon.com. Pros: Portable; fun even for younger kids who don't understand the challenges; variety of challenges provide lasting fun for kids of different skill levels. Cons: Answer key is easy for kids to see.