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Lena's friends followed the "five-second rule": they would eat food that had dropped on the floor, but only if it was on the floor for less than five seconds. Lena thought that bacteria would stick to food as soon as it touched the floor, so the amount of time on the floor wouldn't affect how much bacteria stuck to the food. She placed twelve boiled noodles on the kitchen floor, picked up six after three seconds, and picked up the rest after ten seconds. Then, she touched each noodle to a separate Petri dish used to grow bacteria. After one week, the bacteria that had transferred from each noodle to its Petri dish had grown to visible clusters. Because there were more bacteria on the ten-second dishes than the three-second dishes, Lena reasoned that the amount of time on the floor did affect how much bacteria stuck to the food. She showed her friends pictures of the Petri dishes and a graph of her results.