When one cup starts infected, something surprising happens after just two rounds of sharing solutions: the count of infected cups doubles each time. That doubling pattern is exponential growth in action. As you graph each round, the curve climbs fast — the same way a single bacterium reaches one million in just ten hours. The pink indicator reveals which cups caught the chain reaction, making the spread visible in a way a simple count cannot.

When one infected cup starts a round of sharing, the illness passes to new people — who then pass it to others. As each round of exchanges spreads the clear solution through the group, the pink indicator reveals which cups got infected along the chain. A single source can seed many infections. That pattern of spread, graphed after each round, matches the same exponential growth seen when a single bacterium doubles its way to one million in just ten hours.