Windmill building blocks that are BPA free, odorless, and have rounded edges that do not harm hands. Comes with a "Wind Energy Challenge Card" for children to test and record the speed of lifting weights by changing the number (2/3/4/6 pieces) or shape of blades, and intuitively understand the relationship between "force area torque energy conversion". When the wind stops, it automatically locks to prevent weights from falling, reflecting mechanical safety design. Educational scenario: Predicting which blade number can lift a 100g weight the fastest? Use a rubber band dynamometer to read and record the difference between 3 and 6 blades.