Sidney was a 14-year-old boy with an interest in the sciences. One summer day he started his own investigations¹. With his 12-year-old sister Sophie in tow, he caught a large bull frog in a local pond. Sidney started his experiment with the amphibian², and told Sophie her job was to write down the results of the experiment.

Sidney drew a line in the sand, placed the frog on the line, and prodded³ the frog with a small twig⁴ from the rear and shouted, "Jump, frog!" The frog jumped, and Sidney measured the distance. "12 feet...write that down, Sophie," he said.

Next, he brought the frog back to the starting point and removed the frog's right front leg. Again he prodded the frog and shouted, "Jump, frog!" The frog jumped 10 feet, and on instruction, Sophie wrote it down.

Again the frog was brought back, the left front leg was removed, and again "Jump, frog!" Sidney reported, "Six feet...write it down."

The next time, Sidney removed the large right back leg. "Jump, frog!" Then, he shouted "Jump, frog!" and prodded the frog. "The frog jumped 8 inches...write it down, Sophie."

Finally, Sidney removed the frog's remaining back left leg, put it down and prodded the frog with the twig shouting, "Jump, frog! Jump, frog! JUMP FROG!! JUMP JUMP FROG!!!"

The frog didn't jump. Sophie looked at Sidney, and said, "So what should I write down?"

Sidney thought a moment, then told Sophie to write, "When you remove all the legs from a frog, it turns deaf."