Using Everyday Knowledge of Decimals to Enhance Understanding

The study investigated the role of students' everyday knowledge of decimals in supporting the development of their knowledge of decimals. Sixteen students, ages 11 and 12, from a lower economic area, were asked to work in pairs (one member of each pair a more able student and one a less able student) to solve problems that tapped common misconceptions about decimal fractions. Half the pairs worked on problems presented in familiar contexts and half worked on problems presented without context. A comparison of pretest and posttest results revealed that students who worked on contextual problems made significantly more progress in their knowledge of decimals than did those who worked on noncontextual problems. Dialogues between pairs of students during problem solving were analyzed with respect to the arguments used. Results from this analysis suggested that greater reciprocity existed in the pairs working on the contextualized problems, partly because, for those problems, the less able students more commonly took advantage of their everyday knowledge of decimals. It is postulated that the students who solved contextualized problems were able to build scientific understanding of decimals by reflecting on their everyday knowledge as it pertained to the meaning of decimal numbers and the results of decimal calculations.