This study analyzed changes in high school teachers' ability to identify and create questions that support mathematical understanding as they were participating in a professional development program focused on planning, teaching and reflecting on lessons featuring cognitively challenging tasks. The 35 participants were a subset of nearly 100 high school mathematics teachers from a large urban district participating in the professional development program. Data related to questioning abilities was collected via a pre- and post-test that situated questioning within the practice of teaching Algebra. To account for changes in teachers' abilities related to questioning, demographic data describing the participants was collected. In addition, attendance sheets, agendas and materials from the professional development sessions and responses to two prompts at the conclusion of the program were collectedAnalysis of data related to questioning indicated that participants significantly increased their abilities to identify and create questions that promote understanding of mathematics, particularly questions that prompt students to explore mathematical ideas and connections. Asking this type of question has been linked to increased student achievement. However, most teachers rarely, if ever, ask this type of question. An analysis of demographic data showed that the significant changes in teachers' questioning abilities were not associated with years of teaching experience or the high school or sub-district at which the teacher taught. In addition, analysis of data from the professional development program indicated that changes in teachers' questioning abilities were not associated with any one of the four facilitators of the professional development sessions. Participants in the study, as well as teachers not participating in the study but participating in the professional development program, had a high attendance rate for the professional development sessions. During these sessions, teachers had a variety of opportunities to learn about and discuss aspects of questioning, including solving and discussing challenging mathematics tasks; analyzing and discussing episodes of teaching Algebra; analyzing and generating questions for student work from Algebra classrooms; and analyzing and planning lessons related to the Algebra curriculum
