It is considered that fraction concepts are difficult to teach/learn in Japan's elementary schools. There are a lot of factors including the following: ・A variety of the meanings, the complexity of the meanings, and the complicated notations for fractions (Ishida, 1985) ・The continual argument about introductory lessons for fractions ・The appearance of new meanings for fractions in the third grader's mathematics textbooks and some theories In addition, children's everyday concepts of fractions have been taken into little consideration in teaching/learning fraction concepts. In other words, the following have not yet been explained. 1) What everyday concepts of fractions do children have, before they begin learning fractions at school? 2) How are children's fraction concepts formed through fraction lessons, based on their everyday concepts of fractions? 3) What teaching/learning are suitable for fraction lessons when we consider children's everyday concepts of fractions? This paper answers the first problem. That is, the purpose of this study was to clarify children's everyday concepts of fractions. Here, everyday concepts, and mathematics concepts corresponding to the scientific concepts are defined by Vygotsky's theory. Three investigations were conducted to clarify children's everyday concepts. In the first investigation, six third grade children were interviewed to collect information for a questionnaire (Yoshida, 2000). In the second one, twenty-one second grade children were interviewed using not only a questionnaire but also some concrete objects such as ribbons, Origami (folding papers), kumquats (small oranges), and sliced cakes and cookies made of cardboards etc. Finally, thirty-nine third grade children were given questionnaires as a test at the same time without any concrete objects. All children have not learned fractions at school at all. The first and second investigations were recorded on videos and tape recorders. The results from the second study, particularly, reflected the children's everyday concepts of fractions of the three investigations, because it was conducted in the most realistic everyday context using concrete objects. Moreover, the children were younger. The questionnaires for the second and third investigations were the same but different from the first one. They were based on the result from the first study, and were classified into six categories: (I) equipartition, (II) a view of unit '1', (III) quantity sense, (IV) equivalence, (V) order, and (VI) comparison between two quantities. Finally, children's everyday concepts of fractions were clarified for each category. And furthermore, the children's everyday concepts of fractions were integrated concisely into the following: EF1) Equipartition concepts that are used when children partition the whole equally by regarding the whole as a unit '1' EF2) Construction concepts that are used when children construct a unit '1' subjectively corresponding to an integer EF3) Identification concepts that are used when children identify a unit '1' subjectively corresponding to an integer according to the existing scale EF4) Identification concepts that are used when children identify the objects which has no scale, severing the connection with the whole EF5) Quantity concepts that are used when children consider the quantities in a real context EF6) Fundamental concepts for equivalent fractions that are used depending on the contexts EF7) Basic concepts for ordering fractions that are used in everyday concepts
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