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.

## Search Results

### Diagonals to Quadrilaterals

9-12
This interactive allows users to investigate three types of quadrilaterals; ones with: perpendicular bisectors, congruent perpendicular bisectors, and congruent bisectors.

### Handshakes

3-5, 6-8

When the nine justices of the Supreme Court meet, they greet one another with a handshake to show harmony of purpose, even though their views may differ. How many handshakes occur? In general, how many handshakes occur when there are n people?

### Bunny Times

Pre-K-2, 3-5

Become confident in facts up to 12 x 12 using visual models that stress the conceptual aspects of multiplication.

### Geogebra: Residuals and Linear Regression

9-12
Explore linear regression and residuals using this Geogebra interactive.

### Using an Elevator to Evaluate Signed Number Expressions

6-8, 9-12

Using an Elevator to Evaluate Signed Number Expressions Using the idea of an elevator moving up and down, students will be given a small set of rules to add and subtract signed integers. The idea behind the method of adding and subtracting signed integers offered in these lesson is that the number of rules that s

### Can You KenKen?

3-5, 6-8
The objective of this lesson is to use combinations to solve KenKen puzzles. An early solution strategy is for students to guess and check and use logic-based elimination. This lesson builds on those strategies by having students systematically list all possible combinations within each cage, the darkly outlined sections of the puzzle.

### Geogebra:Dynagraphs

6-8, 9-12

Explore relationships between inputs and outputs by manipulating interactive double number lines.

This interactive is optimized for your desktop and tablet.

### Simson Line

9-12
This applet allows for the construction and exploration of the Simson Line.

### Isosceles Triangle Area

6-8
Explore when an isosceles triangle obtains its maximum area.

### Soccer Problem

9-12
Where should a soccer player be placed so that she has the best chance of making a goal?