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.

Pre-K-2, 3-5, 6-8, 9-12
Standards:
Math Content:
Data Analysis and Probability

Change the number of sectors and increase or decrease their size to create any type of spinner. Then, conduct a probability experiment by spinning the spinner many times. How does the experimental probability compare with the theoretical probability?

This interactive is optimized for your desktop and tablet.

### Features

• Click the  and  buttons to change the number of sectors.
• Adjust the sliders  to change the size of the sectors.
• Change the name of each sector by clicking on the text, under the column, "Color."
• Click the Pie Chart button  to see a experimental graph. (It is interesting to leave this open as you continue to spin the spinner. The pie graph is automatically updated with each spin.)

### How to Use

To run an experiment, enter a number in the "Number of spins" box. Then click Spin. The experimental and theoretical probabilities will be shown in the table. Hit the Spin button repeatedly to get more trials, or hit Skip to End, after hitting the spin button once, if you would like for all the spins to generate.

To start over, click Reset.

Create a spinner of your choosing. Add or delete sectors, change their sizes and colors, go wild.

Make sure the Number of Spins is 1, and click the Spin button.

• How does the experimental probability compare to the theoretical probability?
• Click the Spin button a few more times. What happens?

Change the Number of Spins to 100, and click the Spin button.

• How do the experimental and theoretical probabilities now compare?
• Hit the Spin button a few more times. What happens?
• What would you expect to happen if you hit the button many times?

Increase the Number of Spins to a very large number (the maximum allowed is 99,999).

• Hit the Spin button one or more times?
• Now compare the theoretical and experimental probabilities. What do you notice?