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Interactive
National Council of Teachers of Mathematics

Nctm: Illuminations: Scale Factor

For Students 3rd - 8th Standards
The interactive applet allows learners to explore the relationships between side length, area, and perimeter. Students see how changes in the scale factor influence the ratio of areas and perimeters. [Requires Java.]
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Interactive
National Council of Teachers of Mathematics

Nctm: Illuminations: Proof Without Words Completing the Square

For Students 9th - 10th
Students use this computer applet to visualize the concept of completing the square.
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Interactive
National Council of Teachers of Mathematics

Nctm: Illuminations: Circle Area

For Students 3rd - 8th Standards
Explore what the relationship the radius has to the area of a circle. Click the instructions to learn how to use this interactive resource and select"Exploration" for more ideas.
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Interactive
National Council of Teachers of Mathematics

Nctm: Illuminations: Fraction Concentration

For Students K - 1st Standards
Click on the "Cards" dropdown menu and choose "Fractions". Play concentration matching fractions, fraction words, and visual representations for fraction amounts. Pick numbers from 1 to 6 or 1 to 10. One or two can play this game.