[Originally published by David Rieck on July 7, 2014]   I started flipping some of the content in my general chemistry class about three years ago. When I began, my classes typically had a maximum of 44 students, but recently I have had classes of 66 and on one occasion 88 students. (Our lectures increase in 22 student increments because that is the number of students per lab.  Thus, adding one more lab section to a class increases the lecture by 22.) While there are certainly some obstacles to flipping larger classes, some of which are out of the instructor’s control, I find that it is still a useful and effective instructional method. In a flipped class, students watch the lecture on their own time, and then spend the class working problems in small groups. The students work through packets of problems progressing from very simple questions to more challenging problems.  The most significant difficulty I encounter in larger classes is making sure I give each group enough of my attention. With anywhere from 10 to more than 20 groups and a total class time that may be only 50 minutes, it becomes a mathematical certainty that some groups will get very little of my time. I am especially concerned that students might think they are doing things correctly when they are not, and they may continue working additional, more challenging problems when they have not mastered the basic concepts. Ultimately such students will run into trouble and they could end up confused and frustrated simply because I was not able to correct some simple errors or misconceptions before they advanced. One way to minimize this particular issue is by using clickers. During class I monitor students’ progress on the packets and when it looks like most groups are finishing a section of problems, I display a similar problem as a clicker question. Groups who answer incorrectly either figure things out on their own, or ask for help before proceeding. Usually only a few groups need help, but this way I can target my attention where it is most needed. The clicker questions definitely help, but I also discovered that fewer students need my help than I had anticipated. It seems that students not only work together within their own groups, but they are also usually very willing to help other groups nearby. I encourage this sort of inter-group association, and emphasize that this sharing of ideas and information is part of how science is really done – science is much more of a social endeavor than most people realize.  A few other difficulties are beyond my control so I just work around them as well as I can. For example, large classes are almost always in lecture rooms that are not designed for group work. It can be hard to get to groups in the middle of seating sections, but students seem to enjoy watching me climb over rows of desks to reach them when they need help. The obstacles I encounter flipping larger classes definitely change how class operates. Most obstacles can be minimized, and others just need to be dealt with as well as possible. In the end, however, even though it is different from a small class environment, I find classroom flipping to be effective, engaging and actually more fun than a traditional lecture. ... View more