INVESTIGATING CHILDREN’S UNDERSTANDING OF THE MEASUREMENT OF MASS JILL CHEESEMAN Monash University Jill.Cheeseman@monash.edu ANDREA McDONOUGH Australian Catholic University andrea.mcdonough@acu.edu.au DOUG CLARKE Australian Catholic University doug.clarke@acu.edu.au In this paper, we discuss the use of a framework of “growth points” in early mathematics learning and a related, task-based, one-to-one interview in assessing children’s understanding of the measurement of mass. Data are presented from a sample of 1806 children in the first three years of school. An example of a child’s responses is given to illustrate the kinds of thinking revealed by interviewing young children about their developing concepts of mass. Background The data discussed are from the Early Numeracy Research Project 1 (ENRP), where teachers and university researchers were seeking to find the most effective approaches to the teaching of mathematics in the first three years of school. At the beginning of the project, the research team identified the need for development of a comprehensive and appropriate learning and assessment framework for early mathematics, and a tool for assessing young children’s mathematical thinking. The inappropriateness of pen and paper assessment at these grade levels (Clements & Ellerton, 1995) led to the development of a task-based, one-to-one interview schedule. The project team studied available research on the development of young children’s mathematics learning in the mathematical domains of Counting, Place value, Addition and subtraction, and Multiplication and division (in Number), Time, Length, and Mass (in Measurement), and Properties of shape and Visualisation and orientation (in Geometry). In this paper, the focus is on the Measurement domain of Mass. While much has been published about children’s concept development in the measurement of Length (e.g., Clements & Sarama, 2009; Lehrer, Jenkins, & Osana, 1998) and Area (e.g., Outhred & Mitchelmore, 1992), little is published about Mass. However, research has provided some insights. For example, in researching the transitive nature of young children’s ordinal ability, Brainerd (1974), found that 5 year- olds could arrange three balls of clay according to their mass and could arrange sticks according to their length. 1 The Early Numeracy Research Project was supported by grants from the Victorian Department of Employment, Education and Training, the Catholic Education Office (Melbourne), and the Association of Independent Schools Victoria. We are grateful to our co-researchers in ENRP trial for insights that are reflected in this paper. MATHEMATICS: TRADITIONS AND [NEW] PRACTICES • © AAMT & MERGA 2011 174