Classroom utility

Probability Lab

Run a batch of digital coin tosses, record the result, and see how a sample compares with the 50/50 expectation.

Choose a run

Each toss uses crypto.getRandomValues() in your browser. The experiment stays on this page.

Number of tosses 10 tossesQuick demonstration 100 tossesGood class-sized sample 1,000 tossesLarger sample to compare

Choose a run size, then run the experiment.

Heads — Waiting

Tails — Waiting

Heads

Tails

No experiment yet. The expected result is an even split, but a small sample will often differ.

Use the lab to investigate variation rather than to chase a particular answer.

For 100 tosses, would you expect exactly 50 heads? Write down a prediction, then compare it with the result.

Run 100 tosses several times. What changes from run to run, and what stays close to 50%?

Run 10, 100, and 1,000 tosses. A larger sample often looks closer to 50%, but it is not required to be closer every time.

This is a simulation for learning about random variation. It cannot prove that any finite run is perfectly fair.