freezing means substance changes from a liquid into a solid by decreasing heat energy & water starts to freeze & water is a kind of substance ->  water is decreasing in heat energy  water is decreasing in heat energy & temperature is a measure of heat energy ->  water is decreasing in temperature  water is decreasing in temperature & as the temperature of a substance decreases , the molecules in that substance will move slower / closer -> the molecules in water will move slower when the water is decreasing in temperature