Decades of research conducted worldwide has resulted in a taxonomy for word problems involving additive situations. Research published in the 1980s found that U.S. curricula only exposed first-grade students to a small subset of the easiest types of word problems. Widely adopted curriculum standards in the United States call for first-grade…

Understanding how environments influence learning requires attending not only to what is present but also to what is absent. In the context of mathematics learning, this means attending not only to problems that children encounter frequently in textbooks but also to ones that appear rarely. We present research in this article showing that students…

Many children fail to master fraction arithmetic even after years of instruction, a failure that hinders their learning of more advanced mathematics as well as their occupational success. To test hypotheses about why children have so many difficulties in this area, we created a computational model of fraction arithmetic learning and presented it…