Children's Understanding of Approximate Addition Depends on Problem Format

Studies suggest that five-year-old children can add and compare large numerical quantities through approximate representations of number. Recently, it was shown that preschool children have an advantage for canonical problems (i.e., arithmetic operations presented on the left-hand side of space). The present study will examine whether older children have this same advantage. Children (M age = 7.93 years) viewed events that required them to add and compare large symbolic numbers, which disappeared quickly in order to get children to estimate. These events were shown either in the canonical or the non-canonical format. The dependent variable was the number of problems solved correctly (out of 8). It was found that, in contrast to preschool children, older children performed better on the non-canonical problems than on the canonical problems. It is posited that second-grade children associate the canonical format with adding exactly, which makes it more difficult for them to draw on their approximate number system.