Abstract
This study investigates the effects of the number line on students’ solution of additive change problems. We organized an experimental program focusing on the use of the number line in coordination with other representations in additive problem solving and compared its outcomes with the results of the regular mathematical curriculum. The experimental group consisted of 356 students, while the control group included 776 students in Grades 1, 2 and 3 of primary school. The data were collected using change problems of various structures in two types of representation, verbal description and verbal description with number line. Confirmatory Factor Analysis showed that the type of representation had an effect on the solution of additive problems of a complex structure, but not in the solution of simple problems. The experimental group students of Grades 1 and 2 performed better than the control group students in all types of problems irrespectively of the representation. The use of the number line was a complex but an efficient way of solving a number of additive problems. It supported problem solving for representing either the situation or the solution of the problem.