Travel-Friendly Educational Toys: Thanks to its compact size and portable travel case. Can you find the missing link? Fit all puzzle pieces on the game board. There are 36 puzzle parts but only 24 free places on the game board! Open rings and balls of different puzzle pieces can occupy the same place when you link them the right way. These 120 challenges (with solutions) will help children age 8 and above to stimulate their cognitive skills such as Concentration, Problem Solving and Spatial Insight.