“People rely on this ability in daily life,” Mazzocco said. “A familiar example is when people size up which line will move more quickly at the grocery store, based on their perception of the number of persons and items per line.”

The researchers compared children’s ability to estimate quantity with their level of mathematics achievement.

To conduct the study, the researchers gave 71 ninth graders two series of tests designed to measure their ability to estimate quantities, a capability governed by what the researchers referred to as the approximate number system (ANS). The students were a subset of a larger sample of 161 students from Mazzocco’s ongoing long-term research study. The children’s math abilities had been tested at regular intervals since kindergarten.

The ninth graders were classified into four groups, based on math achievement scores they had received since kindergarten:

  • above the 95th percentile (high achieving)
  • 25th to 95th percentile (typically achieving)
  • 11th to 25th percentile (low achieving)
  • 10th percentile and below (math learning disabled)

For the first series of ANS tests, the students viewed a computer screen showing a group of blue and yellow dots, and were asked to say whether more blue or yellow dots appeared.

In the second series, nine to 15 dots of one color appeared, and the students were asked to say how many dots they saw.