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?

### Instructions

 Click the +1 and -1 buttons to change the number of sectors. Next to the names of the colors, adjust the sliders or enter values into the percent boxes to change the size of the sectors. 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 at the bottom. Hit the Spin button repeatedly to get more trials. Click Show Results Frame to see a pie graph of the results. (It is interesting to leave the Results Frame open as you continue to spin the spinner. The pie graph is automatically updated with each spin.) To start over, click New Experiment.

### Exploration

 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? Was your prediction correct?

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### NCTM Resources

Navigating through Probability in 3‑5

### Lessons

 More and Better Mathematics for All Students
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