The Challenge of Providing a College-Level Course
The College Board developed the AP Chemistry course to be equivalent to an introductory chemistry course at the college/university level. The classroom portion of the AP course should incorporate more advanced topics than a typical Chemistry I or even honors-level course. By the same token, the laboratory work should be more sophisticated in terms of not only the topics investigated but also the level of data treatment and interpretation.
In this article, I suggest ways to help teachers establish new AP laboratory programs or improve upon existing ones. I assume that readers are familiar with the recommendations set forth in the 2007, 2008 AP® Chemistry Course Description. This Course Description specifies the desired standards for the laboratory portion of the course in terms of time, facilities, and equipment and provides a list of 22 recommended experiments to guide both beginning and experienced teachers in designing their programs.
Essential Facilities and Equipment
High schools should first determine whether they have the appropriate facilities to offer the AP Chemistry course. The Course Description suggests that a dedicated space be available where students can leave experiments out overnight if necessary. Although most colleges do not have this luxury, it is essential that high schools schedule the AP Chemistry course in a single room so teachers and students do not have to move equipment and supplies from room to room.
It is notable that the 22 experiments listed are "recommended" rather than "required" and that none of these experiments list specific procedures. While the task of setting up a lab program might be easier if the Course Description specified certain experiments or procedures, the AP Chemistry Development Committee leaves these details up to individual teachers, who are encouraged to take advantage of the breadth of chemistry and the variety of experiments that students can perform in any single area.
When setting up a program, teachers should be sure to include a broad range of experiments involving a variety of experimental techniques, many of which should be quantitative in nature. The quantitative expectations require a high-precision balance (1 mg sensitivity or better) and a variety of volumetric glassware (burets and various sizes of pipets and volumetric flasks). Obviously, a great deal of additional "standard" glassware is listed in the Course Description. Students should conduct quantitative experiments with appropriate consideration for the accuracy and precision characteristic of the equipment they are using. (For example, in our general chemistry course, we have one top-loading balance for every four students.)
Spectrophotometers and pH meters are also important components in the quantitative arsenal of a modern laboratory and increase the diversity of experiments that students can carry out. If the cost of these items exceeds the funds available, schools should consider purchasing data-acquisition probes since these devices can achieve many of the same measurements at a fraction of the expense. Further, because schools can purchase these probes piecemeal (that is, one probe at a time), they can distribute the cost over more than one budget year.
Doing More with Less (Time)
While the goal of an AP Chemistry laboratory program should be to provide in-depth activities for each of the 22 recommended experiments, this may not always be possible due to time limitations. In these circumstances, it is better to perform more short experiments than fewer, longer activities. Teachers can decrease the time needed to obtain results in many experiments by performing them on a microscale level. Students can use the time saved in this way for conducting more trials of the same experiment, making it possible to carry out meaningful statistical analyses. Alternatively, teachers can use the time to increase the range of topics treated. Although microscale activities are inherently less accurate and/or precise than many macroscale ones, they afford more-than-satisfactory results when the goal is to illustrate a principle rather than to carry out an analytical determination. You can find examples of microscale experiments in a suitable laboratory manual or in the "Microscale Laboratory" column of theJournal of Chemical Education.
By combining the recommendations made in the AP Chemistry Course Description with the suggestions in this article, any teacher should be able to establish a successful AP Chemistry laboratory program.
Arden P. Zipp is a Distinguished Teaching Professor at State University of New York College at Cortland in Cortland, New York. He has served in every capacity for the College Board in the development and scoring of the AP Chemistry Exam: he has been a Reader, Table Leader, Question Leader, Chief Reader, and Development Committee member and chair. He was also the Chief Examiner for IB Chemistry for many years and is currently the chair of the U.S. National Chemistry Olympiad Examinations Task Force. He has authored many publications and is a coauthor of Chemistry in Context. He has made over 230 presentations at local, regional, national, and international meetings, including more than 60 AP Chemistry workshops and summer institutes.