摘要：AbstractThis study attempts to answer the question: “how well do preservice elementary teachers identify the necessary and sufficient conditions for a rhombus?”. Forty-five elementary preservice teachers were interviewed individually on a rhombus task. They were given four quadrilaterals and asked which of them was not a rhombus. Interview transcripts were analyzed and coded by each researcher independently. Findings have showed that some of the participants noticed many properties of a rhombus, but they did not see the relationships between the properties. Hence they could not reduce the list of properties to a concise definition with necessary and sufficient conditions.
关键词：preservice teachers;rhombus;necessary and sufficient conditions;geometric thinking level
