[Date] To Whom It May Concern: This letter confirms that [Name] has successfully completed [#] hours of professional development at a Math Teachers’ Circle at [HOST INSTITUTION] in [CITY]. [NAME] attended the [NAME OF MTC] Math Teachers' Circle on the following dates: [List of dates] The [NAME OF MTC] Math Teachers’ Circle is a professional community of K-12 mathematics teachers and mathematicians in [LOCATION]. Our group meets regularly to work on rich mathematics problems, allowing teachers to enrich their knowledge and experience of math, while building meaningful partnerships with other teachers and mathematicians. The [NAME OF MTC] Math Teachers’ Circle has been offering professional development to [LOCATION] teachers since [YEAR]. We are a member of the Math Teachers’ Circle Network (www.mathteacherscircle.org), which includes more than 100 circles in 38 states. The [NAME OF MTC] Math Teachers’ Circle is sponsored by the American Institute of Mathematics in San Jose, CA — one of the eight mathematics institutes funded by the National Science Foundation with the mission of promoting mathematics learning and research. We are also sponsored by [LIST OF SPONSORS]. If you have any questions, please feel free to contact me. Best regards, [NAME]