This is the standards chapter in the Principles and Standards for School Mathematics of the National Council of Teachers of Mathematics. Select Geometry from the left column for across-the-grades standards. For specific grade level standards select Pre-K - 2, 3 - 5, or 6 - 8, from the top row. (
http://standards.nctm.org/document/chapter3/index.htm
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An interactive lesson for investigating triangles and polygons on geoboards from the electronic examples of the Principles and Standards for School Mathematics. (Pre-K-2) (
http://standards.nctm.org/document/eexamples/chap4/4.2/index.htm
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An interactive lesson with Tangrams from the electronic examples of the Principles and Standards for School Mathematics. (Pre-K-2) (
http://standards.nctm.org/document/eexamples/chap4/4.4/index.htm
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Complete information on tessellations including definition, math significance, history, and tutorials. (
http://forum.swarthmore.edu/sum95/suzanne/tess.intro.html
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