The UNC-CH Department of Physics & Astronomy has completed a multi-stage transformation (begun in 2004) of our introductory physics instruction, in which we created four new courses to provide students with education in exciting and relevant physics topics using effective, research-validated pedagogy. These courses were launched in the 2014/15 academic year, and now provide physics instruction for over 1600 students each year. These classes allow every student to take full advantage of active learning, guided by the findings of an extensive body of physics education research. Our current lecture/studio pedagogy, which has the students spending 2/3 of their class time each week working in small groups on structured hands-on and minds-on activities (conducted in classrooms renovated for the purpose), was compared to traditional methods in an MS thesis recently defended by one of our graduate students, David Guynn (who is also a UNC staff member). It is very clear from the data (and its rigorous analysis) that significant learning gains result from the new mode of instruction compared to the old, for all student populations and regardless of the instructor. The transformation we have accomplished goes well beyond individual efforts to improve large lecture classes in other departments. We chose to work together as a department to undertake these changes, rather than as individual faculty members, in order to make the changes more comprehensive and sustainable. In so doing we have taken as scientific an approach to our teaching as we do to our research, in order to benefit our students.