Isaac’s Jump Line

Isaac and Millie were making a jumping game in the playground. Their teacher drew a chalk line for the start. “Land on two feet,” she reminded them. Isaac jumped first. Millie marked the back of his heels with chalk.

Millie jumped next. Her landing mark was farther from the starting line. “How much farther?” asked Isaac. They could see that her jump was longer, but looking alone did not tell them the difference.

Their teacher brought identical wooden strips for measuring. Isaac laid them from the starting line towards his mark. He left a gap after the first strip. Millie noticed it. “That space is not part of a strip,” she said.

Isaac closed the gap and kept going. Five strips fitted from the start to his landing mark, with no gaps or overlaps. “My jump measures five strips,” he said. They left the measuring row in place.

Millie used the same kind of strips beside his row. Seven strips reached her landing mark. Both rows began at the chalk starting line. “Seven strips for mine,” she said. “Our strips are the same size. We’re using the same units.”

They matched the first five strips in each row. Two strips remained at the end of Millie’s row. Isaac pointed to them. “Your jump is two strips longer than mine. Seven is two more than five.”

Isaac wanted another turn. He bent his knees and swung his arms, just as their teacher had shown them. His next jump reached a little farther. Millie made a new mark, and they measured it carefully together.

Then they wiped away the landing marks and packed the strips away. “I liked finding the difference,” said Isaac. Millie drew a small finishing line for a new game. This time, they would try jumping together.