In this mixed methods case study I examined the impact of daily number talks (or strings) on the development of mental math abilities of second graders within a reform-based classroom. I also looked at whether or not the implementation of number talks would increase studentsβ ability to calculate with accuracy, efficiency, and flexibility. Finally, I looked at whether or not the implementation of number talks would increase studentsβ understanding of place value and number relationships. The sample included one class of 19 second-graders to determine the overall impact of number talks, with a focus on six embedded case studies which amplified how this change occurred. A preassessment interview, two midassessments, twenty-four number talks, a postnumber talk questionnaire, and a postassessment interview were used over the span of six weeks. The twenty-four number talks were developed for students to invent, construct, and make sense of their own number strategies and their underlying key ideas. After six weeks of number talks, all students demonstrated an increase in accuracy, efficiency, and flexibility in their number calculations to 20. The case study data of two low-achieving, three average-achieving, and one high-level student reveals growth in their ability to articulate their thinking with an increase in their understanding of place value and number relationships
