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STC Unit Descriptions
Changes
ISBN 0-89278-981-6
Subject: Changes in the state of substances
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Materials
included in the Changes unit kit.
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Students expand their understanding of solids, liquids, and gases by
exploring changes in state. They investigate freezing, melting, evaporation, and
condensation of water. In a sequence of lessons, students produce a mixture of two solids
and a mixture of solids with liquids and observe the results. They work through several
methods to separate mixtures: sieving, filtration, evaporation, and chromatography. The
students set up races that involve sugar dissolving in water and observe the effects of
particle size and water temperature on the rate at which the sugar dissolves. They also
observe crystals formed as a result of evaporation. Students observe some 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 an effervescent tablet in water. Students have several
opportunities to practice their new skills in lessons in which they devise ways of
separating a mystery mixture and plan and carry out investigations that involve other
changes.
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