  The introduction of active learning into physics education at the university
level may be crucial for improved learning outcomes. In UNIST (Ulsan National
Institute of Science and Technology), introductory physics has been redesigned
to reduce the time spent on unidirectional lectures, while increasing the time
devoted to classroom activities which facilitate the interaction between
students and the instructors, as well as increasing the interaction between
student peers. We measured student achievement and the degree of student
satisfaction in order to evaluate the impact of the new learning methods on
student learning outcomes. In the first semester, we redesigned a class of N_I
= 176 students with a reduction in lecture hours and replaced them with
pre-class self studies and in-class problem solving, and compared it with the
traditional lecture based class of N_II = 161 students. We found that even
though the midterm results of two classes were similar, the final average score
of the redesigned class was 10 points higher than the traditional class. In the
second semester, we applied our strategy to three classes but controlled the
proportion of face-to-face lectures to the entire class meeting hours
systematically to be 1/3 in `Class 1' of N1 = 160 students, 1/2 in 'Class 2' of
N2 = 176 students and 2/3 in `Class 3' of N3 = 177 students. (Abridged)
