We report conceptual inventory results of a large-scale assessment project at a large university. We studied the introduction of materials and instructional methods informed by physics education research (PER) (physics education research-informed materials) into a department where most instruction has previously been traditional and a significant number of faculty are hesitant, ambivalent, or even resistant to the introduction of such reforms. Data were collected in all of the sections of both the large algebraand calculus-based introductory courses for a number of years employing commonly used conceptual inventories. Results from a small PER-informed, inquiry-based, laboratory-based class are also reported. Results suggest that when PER-informed materials are introduced in the labs and recitations, independent of the lecture style, there is an increase in students' conceptual inventory gains. There is also an increase in the results on conceptual inventories if PER-informed instruction is used in the lecture. The highest conceptual inventory gains were achieved by the combination of PER-informed lectures and laboratories in large class settings and by the hands-on, laboratory-based, inquiry-based course taught in a small class setting.