In this video, five-year-old Chris engages in spatial problem solving as he builds with window blocks on a classroom table. Notice how Chris modifies his strategies to accommodate for the effects of physics that he encounters. See how he carefully modifies block orientation and placement in order to find each block’s center of gravity. Notice how he reorganizes his structure to achieve balance. Watch how Chris persistently works to achieve bilateral symmetry in the design of his structure. Also observe the flexibility of Chris’s thinking as he works in a rule-bound fashion. Chris understands that the blocks can be rotated and reoriented. However, in the end each block must be placed in the same orientation in order to achieve bilateral symmetry.