Thank you for your interest in NCTM’s Illuminations. Beginning in mid-April, all Illuminations content will be moving to nctm.org/illuminations. Interactives will remain openly available and NCTM members will have access to all Illuminations lessons with new filtering and search options. We hope you will continue to utilize and enjoy these resources on nctm.org.

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FractionGame
Number and Operations

Fraction Game

3-5, 6-8
This applet allows students to individually practice working with relationships among fractions and ways of combining fractions.
Histogram Tool
Data Analysis and Probability

Histogram Tool

3-5, 6-8, 9-12
This tool can be used to create a histogram for analyzing the distribution of a data set using data that you enter or using pre‑loaded data that you select.
IGDAreaOfAParallelogram
Geometry

IGD: Area of a Parallelogram

3-5, 6-8
This applet will show you how to divide the parallelogram into pieces, arrange them together to form a rectangle, and then use the formula for the area of a rectangle to find the area of the parallelogram.
IGDAreaOfARectangle
Geometry

IGD: Area of a Rectangle

3-5, 6-8
Use this tool to show how the side lengths of a rectangle affect the rectangle's area.
IGDAreaOfATriangle
Geometry

IGD: Area of a Triangle

3-5, 6-8
Use this tool to prove how to find the area of a triangle.
IGDDroppingAPerpendicular
Geometry

IGD: Dropping a Perpendicular Line

9-12
Use this applet to show how to drop a perpendicular from a point onto a line.
AreaOfTrapezoids
Geometry

Area of Trapezoids

6-8
Investigate how changes in the base and height of a trapezoid affect its area.
AreaOfParallelograms
Geometry

Area of Parallelograms

6-8
This applet shows the relationship between the area of a parallelogram and the lengths of its sides.
TriangleInequality
Geometry

Triangle Inequality

6-8, 9-12
This activity illustrates the Triangle Inequality and the conditions necessary for a triangle to be formed from three straight lines.
TriangleClassification
Geometry

Triangle Classification

9-12
Use this applet to show how the placement of the third vertex of a triangle affects the classification of that triangle.