• PiLine IMAGE

    Featured Lesson Plan

    In this grades 9–12 lesson, relate the slope of a line to π. 

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  • Grouping and Grazing

    Featured Mobile Game

    Grouping and Grazing can now be played on your mobile device! Learn to group, tally, add, subtract, and more1 

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  • ShapeSorter IMAGE

    Featured Interactive

    Use this tool to explore many different geometric properties and shapes. 

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  • From1Through19

    Featured Brain Teaser

    Write the numbers from 1 through 19 in the circles so that the numbers in every 3 circles on a straight line total 30.

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