Kids' Mental Number Lines Reveal Math Memory

LiveScience Staff

Date: 10 September 2010 Time: 11:21 AM ET

Kids who visualize numbers as an evenly spaced line are better at remembering the digits than kids who scrunch up the numbers in their heads, according to a new study.

The findings, published in the journal Psychological Science, suggest the way kids visualize numbers reflects their understanding of what the symbols mean.

When children in Western cultures first learn numbers, they place them on number lines from left to right. But the placement is uneven: Smaller numbers are spaced farther apart than larger numbers, which are crunched up toward the end of the line. Gradually, this placement evens out, corresponding with the child's understanding of what the numbers mean, said study co-author Clarissa Thompson of the University of Oklahoma.

"Young children's knowledge sometimes seems impressive, because they can count, 'one, two, three, four, five, six, seven, eight, nine, ten,' but often they just learn by rote," Thompson said in a statement. "Their counting doesn't have much to do with their understanding of how big the numbers are."

To find out how number-line visualization relates to understanding, the researchers gave children a stack of blank number lines with "0" written on the left end and "20" on the right end. Each child heard a series of numbers from one through 19 and had to mark on the number line where they thought that number belonged.

Next, the experimenter told a story that included a few numbers. After the story, the researchers threw off the kids' memories by asking them to name four cartoon characters. Then they asked questions about the story, like "How many forks did Colleen wash?" Children with a more linear number line were better at remembering the numbers in the story.

In three experiments, the researchers found that the more even a child's number line, the better the child was at remembering numbers. This was true for preschoolers for numbers from one to 20 and for elementary school children for numbers from one to 1,000.

"We really do live in a world of numbers," Thompson said. "Some we only need to approximate, and others we need to remember exactly. Ability to estimate the sizes of numbers influences the ability to remember the numbers exactly."