Conditional Probability Visual Lab

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About this simulation

KiwiBee’s rebuilt classroom probability lab uses a uniform sample space and two event intervals. Change P(A), P(B) and their feasible overlap, collect reproducible random trials, and switch between the full population and a population conditioned on A or B. Exact probabilities appear beside observed sample proportions. Changing a parameter starts a fresh experiment; conditioning on a zero-probability event is explicitly undefined. Inspired by Victor Powell’s MIT-licensed Explained Visually activity, with credits to Victor Powell and Lewis Lehe.

What students can explore

Change the overlap and explain how the conditional denominator changes.
Add 100 trials and compare exact probabilities with sample proportions.
Set a conditioning event to zero and explain why its conditional proportion is undefined.

Learning objectives

1Explain conditional probability as a proportion within a restricted population.
2Distinguish P(B|A) from P(A|B).

Questions teachers ask

Who created this activity and what is its source license?

Victor Powell; Explained Visually by Victor Powell and Lewis Lehe. Original source license: MIT. Source: https://github.com/vicapow/explained-visually. KiwiBee improves the classroom controls and experiments, retaining source credits and licenses.

What does this model simplify?

The falling balls are random samples from a simplified model. Short runs fluctuate, and a conditional probability is undefined when its conditioning event has probability zero.

How can I use the activity in class?

Use the activity controls inside the frame, or open fullscreen for a larger workspace. Ask students to predict a result, test it, and explain what changed. The embedded application starts in English; available upstream language controls are part of the original activity.

Embed this simulation

Drop it into your LMS, blog, or class site — free.

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Continue exploring

Spin a spinner, flip a coin or roll a die and watch two sets of bars: the chances the shapes predict, and the results you actually got. Ten spins prove nothing; a few hundred and the two are hard to tell apart.

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Type any function and see its shape straight away. Plot up to three at once in three colours to compare them, drag the trace point to read a value off a curve, and see where each one crosses zero.

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Move m and watch the line tilt; move b and watch it slide. Or drag the two points on the line and read the equation it writes back. A rise-over-run staircase climbs the line so slope becomes something you can count.

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Preview of Two-Body, Three-Body & N-Body Gravity

Compare a two-body orbit with three-body figure-eight motion, then add up to twelve bodies. Change initial masses, velocities and positions; watch orbit trails and numerical energy error.

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Preview of Riemann Sums and the Integral Simulation

Approximate the area under a curve with strips and choose how each takes its height: left edge, right edge, middle, or a sloping top. Push the strip count up and watch the error fall, with the running total plotted as its own curve.

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From model to evidence

Use a worksheet to capture predictions, observations, and explanations after students explore.