Abstract
This paper addresses an effort to design and test a set of items for assessing the mathematics knowledge for teaching. The paper begins by describing how a representative item was developed based on three experienced high school teachers' analyzing classroom instruction. Subsequently, item refinement by two experts is documented. Finally, the initial results of a pilot-test of a focus group of 11 high school mathematics teachers are reported. This study revealed three useful methods for creating items for assessment: (1) using mathematics problems containing certain key mathematical ideas; (2) using nonstandard approaches of students that are unfamiliar to the teachers; and (3) using the errors of teachers.