I: Explanation of Movement; I: Experiments Concerning the Nature of Air; II: The Origin of Wind and of Breath; III: Movement of the Clouds and the Heavenly Bodies; IV: Water Currents and Movements Due to Weight; V: The Child's Idea of Force; II: Prediction and Explanation; VI: The Floating of Boats; VII: The Level of Water; VIII: The Problem of Shadows; III: Explanation of Machines; IX: The Mechanism of Bicycles; X: The Steam-Engine; XI: Trains, Motor-Cars, and Aeroplanes; IV: The Child's Conception of Reality and Causality