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Chemistry LibreTexts

Instructor's Manual

The problem sets on chromatography can be used in at least two different manners.  The primary intent is to use these as a set of in-class, collaborative learning exercises.  Groups of 3-4 students work together in discussing and working through the problems.  When using the problem sets in this manner, the instructor must actively facilitate and guide students through the material.  This manual will guide instructors through each of the problem sets, identifying possible student responses to the questions and the response and activities of the instructor during the progression of the problem. 

An alternative to the use of the problems in class is to assign them as out-of-class activities, preferably done as a group activity among students or as a peer-led learning activity (REF).  The accompanying text that goes with each problem provides a detailed discussion of each step of the thought process of solving it, such that students could work back and forth between the problem and text on an iterative basis to gain an understanding of the material.

There is no perfect way to assemble groups for such collaborative learning activities.  I gather information on the first day of class (year in college, major, prior chemistry courses) and then use this to set groups of 3-4 students that start on the second day of class.  I try to make the groups as heterogeneous as possible and they work together for the entire semester.  Another strategy is to assign groups for a shorter period of time that might encompass completion of a specific topic or unit, and to then create new groups for the next unit.  One other possibility is to have different groups every day of class.  Since it is important for groups to work well together, having new groups every day may be less successful than allowing groups to work together for more extended periods of time.  I would recommend that the instructor assign groups rather than allowing the students to pick their own.  This avoids the potential problem of friends who want to be in the same group but who then do not work well together or stay focused on the assigned task.  It also avoids the problem of the student who is left without a group at the end of the selection process, something that can be especially problematic if it is a member of a minority group.  When using collaborative groups, it is also important for the instructor to monitor the functioning of the groups and to step in to address either dysfunctional groups or the recalcitrant individual within a group. (Ref articles on group learning).  Peer-evaluation processes are often used by instructors who employ group activities as a way of assessing how well groups are working (REF).

I also expect the groups to meet outside of class for any homework assignments, something that is aided because I am at a residential college.  An alternative to this is to schedule a room on the evening before a homework assignment is due and encourage them to come to this place and work in any arrangement they wish on the homework.  I have run such sessions for several years now and attend them as a facilitator (one result is that it has cut down considerably the individual traffic to my office seeking help on the homework problems) and it has been an excellent way to promote collaboration among the students.   

The instructor has an especially important role to fulfill during such group activities.  I have observed that the more engaged that I am in the process in helping to guide the students through the material, the more effective the learning that occurs.  In most instances, it seems that the students are initially stumped by the question, that they begin to explore things that they do know that might apply to answering the question, and that help from the instructor either by letting them know that they are on the right track or by suggesting another direction in which to take their thinking is necessary.  As they begin a question, I roam around the room listening in on conversations and looking over their shoulders at what might be written in their notebook.  If I hear something interesting, I indicate that to the group.  If I see that someone has written something interesting and relevant in their notebook, I tell other group members that they ought to talk with this individual about what they have written, and that the individual should explain to the other group members why they wrote that down.  If I hear a group going entirely in the wrong direction, I probe them on why they are heading in that way and then offer suggestions about things to consider that will set them off in the right direction.  When all groups have realized an important point, I call time out and summarize the concept at the board.  Then I send them back to continue with the next part of the problem.  Most of the problems are handled in such an iterative manner where the students work through some important part of the problem, I summarize it at the board when they have developed the concept, and then they return to the next part of the problem.  Occasionally a group will just not see something, whereas every other group has gotten the point, and it may require a direct intervention from the instructor with that group to explain the concept.  Similarly, there are times when I call their attention to the board to summarize a point when one of the groups still has not gotten the concept but waiting would slow down the remainder of the class to an unacceptable level.

When using these materials, I want the students to discuss and discover the concepts inherent in the problems, so they do not have the text when working on the problems.  After they have completed a particular problem, I then give them a copy of that portion of the text (everyone is instructed to have a three-ring loose-leaf binder of a certain minimum thickness that will accommodate the entire text that will be passed out in increments as the semester develops).  The text thoroughly goes through the thought process for solving each problem and I encourage the students to read it over that evening to reinforce the concepts developed in class that day.  I also give homework problems designed to reinforce the concepts developed in class.