Lighthouse Stairs That Would Not Add Up
On a school trip to Gull Point Lighthouse, Wren's class climbed the spiral stairs to the lamp room. The guide said there were exactly ninety-two steps. Wren liked counting, so she counted on the way up. She got ninety-three.
"You must have miscounted," whispered her friend Bo.
Wren did not think so. On the way down, she counted again and got ninety-three. The guide said ninety-two a second time and shrugged.
Back at school, Wren could not stop thinking about it. She drew a picture of the stairs in her notebook. She realized the guide had counted only the steps, but she had also counted the little stone ledge at the very top, where the stairs met the floor of the lamp room.
At the next visit, she asked the guide if she could check. The guide counted slowly with her, pointing at each step. When they reached the top, he laughed. "Ninety-two steps and one landing," he said. "You are right, and so am I."
Wren wrote both numbers on the back of her ticket. She had learned that two people can count the same thing and still be correct, if they agree on what to count first.