Dr. Callahan is a mathematics associate professor, Math Club sponsor and advisor, and McNair Scholars Program STEM faculty advisor.
Since joining St. Edward's University in 2009, Dr. Callahan has mentored sixteen research students and taught Applied Statistics, Linear Algebra, Calculus I, II, and III, Calculus I Lab, Precalculus, Mathematics for Liberal Arts, Science Seminar, and Science/Mathematics First-Year Seminar. He won the Mathematical Association of America (MAA) Texas Section Ron Barnes Distinguished Service to Students Award in 2018, the School of Natural Sciences Dean’s Excellence in Teaching Award in 2018, the Dean’s Faculty Excellence Award for Research in the School of Natural Sciences in 2015, and the School of Natural Sciences Distinguished Teaching Award in 2014 and was named a finalist for the University Distinguished Teaching Award in 2015. Every year he coordinates trips for students to present their research at regional and national math conferences such as the MAA Texas Section Meeting, Texas Undergraduate Mathematics Conference, Joint Mathematics Meetings, and MAA MathFest.
2018, Ron Barnes Distinguished Service to Students Award, Mathematical Association of America Texas Section
2018, School of Natural Sciences Dean’s Excellence in Teaching Award, St. Edward's University
2015, Dean’s Faculty Excellence Award for Research in the School of Natural Sciences, St. Edward's University
2015, University Distinguished Teaching Award Finalist, St. Edward's University
2014, Presidential Excellence Research Grant, St. Edward's University
2014, School of Natural Sciences Distinguished Teaching Award, St. Edward's University
2011, MAA Texas Section Project NExT Fellowship
2010, MAA National Project NExT Fellowship
2007, Department of Mathematics Outstanding Teaching Award, The University of Texas at Austin
2004, Frank Gerth III Teaching Excellence Award, The University of Texas at Austin
Dawson Neighborhood Association and Planning Contact Team, KUT Public Radio sustaining member, City of Austin Water Conservation Block Leader, named one of "sixty most qualified applicants" for Independent Citizens Redistricting Commission of Austin’s 10-One Redistricting Initiative, helped develop Austin’s first Annual Performance Report and "Dashboard," CityWorks Academy '09
American Mathematical Society (AMS), Mathematical Association of America (MAA), MAA Texas Section, MAA Special Interest Groups on Inquiry-Based Learning, Quantitative Literacy, and Undergraduate Research (SIGMAA IBL, QL, and UR), Academy of Inquiry Based Learning (AIBL), Council on Undergraduate Research (CUR)
MAA Texas Section Meeting, MAA MathFest, MAA and AMS Joint Mathematics Meetings, Texas Undergraduate Mathematics Conference, Geometry of Redistricting Workshop, Texas Undergraduate Topology and Geometry Conference, Legacy of R. L. Moore Conference, Lilly Conference on College and University Teaching and Learning, St. Edward's University Teaching Symposium: A Conference on College Teaching, Texas Hispanic Serving Institutions Consortium Spring Conference, U.S. News STEM Solutions National Conference