This multimedia lesson for Grades 7-10 explores the physical forces that act in concert to create snowflakes. Students build an apparatus that creates conditions similar to a winter cloud and produce their own snow crystals indoors. By watching the snow crystals grow, they learn about how snowflake size and shape is determined by the forces that act on water molecules at the atomic and molecular levels. Digital models and snowflake photo galleries bring together a cohesive package to help kids visualize what's happening at the molecular scale.
Editor's Note: This lab activity calls for dry ice. See Related Materials for a link to the NOAA's "Dry Ice Safety" Guidelines, and for a link to snow crystal images produced by an electron microscope.
6-8: 4B/M15. The atmosphere is a mixture of nitrogen, oxygen, and trace amounts of water vapor, carbon dioxide, and other gases.
4D. The Structure of Matter
6-8: 4D/M1a. All matter is made up of atoms, which are far too small to see directly through a microscope.
6-8: 4D/M1cd. Atoms may link together in well-defined molecules, or may be packed together in crystal patterns. Different arrangements of atoms into groups compose all substances and determine the characteristic properties of substances.
6-8: 4D/M3cd. In solids, the atoms or molecules are closely locked in position and can only vibrate. In liquids, they have higher energy, are more loosely connected, and can slide past one another; some molecules may get enough energy to escape into a gas. In gases, the atoms or molecules have still more energy and are free of one another except during occasional collisions.
9-12: 4D/H2. The number of protons in the nucleus determines what an atom's electron configuration can be and so defines the element. An atom's electron configuration, particularly the outermost electrons, determines how the atom can interact with other atoms. Atoms form bonds to other atoms by transferring or sharing electrons.
9-12: 4D/H7a. Atoms often join with one another in various combinations in distinct molecules or in repeating three-dimensional crystal patterns.
12. Habits of Mind
12C. Manipulation and Observation
6-8: 12C/M3. Make accurate measurements of length, volume, weight, elapsed time, rates, and temperature by using appropriate devices.
<a href="http://www.compadre.org/portal/items/detail.cfm?ID=12568">WGBH Educational Foundation. Teachers' Domain: Why Do Snowflakes Come in So Many Shapes and Sizes?. Boston: WGBH Educational Foundation, 2010.</a>
Teachers' Domain: Why Do Snowflakes Come in So Many Shapes and Sizes?. (2010). Retrieved August 21, 2014, from WGBH Educational Foundation: http://www.teachersdomain.org/resource/lsps07.sci.phys.matter.lpsnowflakes/
WGBH Educational Foundation. Teachers' Domain: Why Do Snowflakes Come in So Many Shapes and Sizes?. Boston: WGBH Educational Foundation, 2010. http://www.teachersdomain.org/resource/lsps07.sci.phys.matter.lpsnowflakes/ (accessed 21 August 2014).
Teachers' Domain: Why Do Snowflakes Come in So Many Shapes and Sizes?. Boston: WGBH Educational Foundation, 2010. 21 Aug. 2014 <http://www.teachersdomain.org/resource/lsps07.sci.phys.matter.lpsnowflakes/>.
%T Teachers' Domain: Why Do Snowflakes Come in So Many Shapes and Sizes? %D 2010 %I WGBH Educational Foundation %C Boston %U http://www.teachersdomain.org/resource/lsps07.sci.phys.matter.lpsnowflakes/ %O application/pdf
%0 Electronic Source %D 2010 %T Teachers' Domain: Why Do Snowflakes Come in So Many Shapes and Sizes? %I WGBH Educational Foundation %V 2014 %N 21 August 2014 %9 application/pdf %U http://www.teachersdomain.org/resource/lsps07.sci.phys.matter.lpsnowflakes/
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