In-class example problems that students work out on their own using active problem-solving are typically well received and help the students better learn the material; however, they are difficult to enact in large classes with limited resources due to the number of questions received and the speed at which different students work through the problem. In a Junior-level mass transfer unit operations course, immediate feedback (IF-AT) forms were used to allow groups of four students to self-pace through in-class problems. The immediate feedback forms allowed students to check their progress, use cooperative learning to resolve their misconceptions, and ask the instructor questions only when truly stuck. In a class of 100 students, with one instructor and one teaching assistant, two problems were worked through, once in week 5 and the other in week 13, using the immediate feedback forms. Student and instructor feedback was highly positive.