How it works
This probability spinner has six equal sections: three say A, two say B, one says C. In theory A wins 3 spins in 6, B 2 and C 1. Spin, and the tally counts what really happens.
Read the full guide
Make a spinner of your own
Type one line for each section in Your sections. A label on two lines gets twice the share, and the wheel redraws as you type. Three to try: A, B, C, D on four lines (1 in 4 each); the numbers 1 to 8 (an even number wins 4 times in 8); A on five lines, B on two, C on one (5, 2 and 1 in 8).
Theoretical and experimental probability
Theoretical probability is a label's lines over all the lines: A is 3/6, or 1/2. Experimental probability is its wins over the spins so far. After 20 spins expect about 10 A, 7 B and 3 C. After 60 expect 30, 20 and 10.
Tips
- Color words work as labels, but the wheel paints slices in its own colors, so letters read better.
- C misses all of the first ten spins about 1 time in 6. A zero is not a broken spinner.
- Under More options, press Clear results between groups, so every group's 20 spins start from zero.
Questions and answers
How do you find the probability of a spinner landing on a section?
When every section is the same size, count the sections with that label and divide by the number of sections. On the opening spinner B is on 2 of 6 sections, so its probability is 2/6, or 1/3.
How is a spinner for probability used in class?
Students work out each label's chance, predict the counts for 20 spins, spin, and set the tally beside the prediction. The two rarely match exactly: A lands on 8 to 12 of 20 spins only about 3 times in 4.
What is a good probability game spinner for two teams?
Use the opening one. Each team picks a letter, the class spins 20 times, and the letter with the most wins takes the round. It is unfair on purpose: A should win most rounds. The task is to retype the list so it is fair.
Can I set a percentage for each section?
Only with repeats. Every line is one equal section, so 25 percent is a label on 2 of 8 lines. Once you type your own list, the line under it gives the chance of the most repeated label.
Why does my tally not match the probability?
Each spin is random and knows nothing of the last one, so a short run can sit far from the fractions. Shares settle toward them over many spins: A takes 40 to 60 percent of 60 spins about 9 times in 10.