Natural systems like rivers and lakes follow mathematical rules to change over time. Researchers studied how people understand these changes visually versus numerically. They used a tank with inflow and outflow tubes to test this. People were better at estimating changes when they saw the objects moving in and out of the tank compared to just looking at numbers. They were most accurate when the inflow equaled the outflow. Seeing the whole system visually helped people understand it better than just looking at numbers.