Changes  (STC)
In Changes, students first expand their understanding of solids, liquids, and gases by exploring changes in state. They investigate freezing, melting, evaporation, and condensation of water.
Then, through a sequence of lessons, they produce mixtures of two solids and of solids with liquids and they observe the results. They work through several ways of separating mixtures: sieving, filtration, evaporation, and chromatography. The students set up dissolving races with sugar and water, in which they observe the effects of sugar particle size and water temperature on the rate at which the sugar "disappears."

Students observe changes that occur immediately and some that occur over time, and they begin to recognize the characteristics of chemical reactions. They investigate rusting, and they observe and collect the gas formed by mixing Alka Seltzer® and water.

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