IconVault's Probability Lab makes the law of large numbers visible. Pick an experiment, coin flip, dice roll (six) or the Monty Hall problem with both switch and stay strategies, set 100 to 100,000 trials and run a Monte Carlo simulation. A convergence chart plots the observed win rate against the theoretical probability as trials grow, with the gap between them reported in percentage points.

It is free and runs fully in your browser, and you can copy the results as plain text for homework or notes. The honest limit: the simulation uses pseudo-random numbers from your browser, which are fine for learning but not for cryptography or real gambling analysis. With few trials the observed rate can sit far from theory; that noise shrinking as trials grow is exactly the lesson.