The purpose of this mixed methods study was to investigate the implementation of a researcher-created numberless word problem instructional unit designed to introduce second-grade students to word problems in the semantic category of "compare with the word more, smaller unknown." The 10-day instructional unit incorporated three elements:…

The use of different registers to represent mathematical concepts enhances understanding. For example, rational numbers can assume pictorial, symbolic and natural language representations and this kind of change improves learning. Based on these assumptions, a teaching experiment for the learning of rational numbers by 2nd grade students was…

Numerical estimation has been used to study how children mentally represent numbers for many years (e.g., Siegler & Opfer, 2003). However, these studies have always presented children with positive numbers and positive number lines. Children's mental representation of negative numbers has never been addressed. The present study tested children…