Moving pictures, movies, animations, or even moving cartoons can be used to teach schematic relationships in complex instrumentation (1-3). While simplistic animations are available on the ancillary CD-ROMs sold with freshman chemistry texts, the Web holds a much wider variety of animations useful in teaching below and above college freshman chemistry (1). Internet-capable computers with a color monitor and relatively fast connection are therefore required. Browser-based animations using free plug-ins such as QuickTime, Shockwave Flash, and Windows Media Player are now as powerful as most users need and the plug-ins are free (3, 4).

Searching for Animations on the Web

Search phrases I have found useful in finding animations on the Web include "quicktime and chemistry", "shockwave and chemistry", or the word "movie" combined with a particular analytical method like "chromatography". Sites listed below are among many that at present host animations that can be used to teach chemistry. A general clearinghouse for chemistry-based animations is The Chemist's Art Gallery.

When you find the animation you want, run it in your browser or click on the link and download the file to your hard drive. If you don't have Web access in the classroom where you want to teach with the animation, open the downloaded file from your hard drive with your browser; no Internet connection is needed.

Teaching Instrumentation with Images or Animation

Obviously, movement in chemical animations can be used to display molecular rotation, movement, or atomic changes. Chime-based or RasMol-based molecular animations (5) do that very nicely. But I have also used animations to teach concepts such as chromatography, hydride generation atomic absorption spectroscopy, the photoelectric effect, the Antarctic ozone hole, and X-ray fluorescence spectroscopy. For viewing animations, take advantage of any file controls that are available to stop, start, back up, or move forward in the animation. In Figure 1, iconic buttons linked to each of the preceding scenes in the animation allow users to pause and restart the animation and to move quickly backward to review an earlier concept. Flash animations, as you'll read below, are very small but, unlike QuickTime formatted animations, won't allow moving backward or forward frame by frame.

Figure 1. A screen shot from an animation that teaches how a grating works in a simple monochromator. The icons along the right side allow pausing, restarting, and moving to previous "scenes" in the animation.

The way I approach teaching with computer animations is to stop on frames where things happen, zero in (in time) on complex relationships, or run the animation backwards so that cause-and-effect relationships can be more clearly understood (1, 2). While my Flash animations aren't programmed to be able to run backwards (yet), the QuickTime format of these same animations--which I place side by side with the Flash files on my animations Web page--will allow running in reverse, and the user can make the animation run backward or forward at will with a click. QuickTime animations can be run in reverse.¹ Flash animations can't be run backwards, but navigation buttons can be added to move to earlier "scenes" in the animation.

I have found in teaching about GC/MS that one of the most difficult concepts for my students to understand is how gas chromatographic (GC) compounds are ionized, how the fragments are subsequently separated in a mass spectrometer, and most specifically how the data are generated by this powerful instrument. I created a Flash animation to teach GC/MS. While showing the animation to the class using a computer/multimedia projector, I pause the animation's action at the point where a compound that has eluted from the GC column is about to pass through the electron impact source. In this way students can get an idea of the chemical processes occurring. I start and then immediately stop the animation when the compound has passed through the electron beam so students can see the ionized fragments (see Fig. 2). Since two "compounds" (compounds ABC and DEF) pass through the ionization source in this part of the animation, I repeat this process so everyone can get it.

Figure 2. The ionization chamber of a GC/MS paused with a GC compound that has just been fragmented in the electron beam.

The next "scene" in the animation involves the entire process that occurs in the mass spectrometer (see Fig. 3). Again, choosing either backward or forward animation movement highlights the process that generates the mass spectrometer's total ion current (TIC) and also clearly demonstrates the difference between the TIC and the mass spectra available from each MS scan, something that is hard for students to comprehend.

Figure 3. A screen shot of the entire mass spectrometer and data generation process in GC/MS. The total ion current (TIC) and a scan's mass spectrum are shown simultaneously to help students differentiate between the types of data generated by this powerful method.

In other words I don't approach dynamic animation tools in a static way. Starting a movie at the beginning and passively running though the entire set of images is, in my mind, wasted use of an excellent tool for teaching complex ideas. As I teach with animations in class, I let my students tell me where to pause the animation. I assign Web-available animations as homework and require students to view the animations online from either home or school and to comment via our online class discussion group. I also assign enough chapter-based chemistry problems for the entire class and require each student to post detailed answers to two or more of the assigned (instrument-based) problems. Students choose the problems they would like to answer online, but it's first come, first served. If the answer to a question has already been posted, it can't be posted again; however, another requirement is that students respond to another student's post and double-check the posted answers. This encourages early involvement with the assignment. Since our discussion group software (a product called Blackboard) time-stamps each post, it is easy to keep track of who posts what and when. Students have even voluntarily started to use HTML code in their chemistry-based discussion posts so subscripts, superscripts, and other appropriate formatting no longer have to get short shrift in their detailed scientific writing.

Occasionally, I use a looping QuickTime animation with the multimedia projector in my classroom as the basis or a test question during an exam. For instance, in testing about internal combustion engines in environmental chemistry, I have students describe the differences in the chemical mixtures entering and exiting the combustion chamber, or I ask them to compare the combustion efficiencies of four-cycle and (two-cycle engines) given the design characteristics displayed in a looping animation.

If you choose to construct images and animations, there are many ways to approach it, but here are a few suggestions. Use colors to your students' advantage; this adds another dimension and information level to the ideas you are trying to teach. Watch NOVA, the PBS television program, or read the magazine Scientific American for examples of, in the first case, complex state-of-the-art scientific animations and in the second, complex images, both using color and perspective to great advantage. Add animation controls to your final product so users can stop, restart, and back up inside animations you create. Shockwave Flash allows you to place buttons anywhere in order to move wherever you choose in an animation; QuickTime controller allows viewers of that format to pause, restart, run in reverse, and back up while viewing.

Finally, consider the final file size for animations you create; large files that take a long time to download on the Web simply won't be viewed (2). File size can be controlled to a degree by choosing a very small file format like Shockwave Flash or by limiting the frame size of the animation in QuickTime or Media Player files and then choosing a powerful compression scheme. Full-screen movies are not always necessary to get your concepts across. For example, with appropriate size choice of labels and fonts, even 400x400-pixel movies can be useful. I include simple GIF animated versions of my movies for those few users without Flash, QuickTime, or Media Player capability. While GIF animations do not support sound, most mod-ern animation authoring software allows saving files in the simple GIF animation format that can be read by all modern Web browsers without any plug-in required (6). GIF animations are simply multiple frames, played one after the other like a child's flip book or the famous series of galloping horse images that made one of the historically earliest movies (7).

Copyright Considerations

Don't save--onto a public server--animation files you download unless you have the author's permission. As an author I am almost always open to requests to place my files on external sites if clear acknowledgment is given. Remember that just because files can be easily copied does not mean that they are not protected by copyright (1).

Note

1. To run a QuickTime animation backwards (on the Macintosh platform), press the keyboard's left arrow button while holding down the command key. To initiate backward, frame-by-frame play on Windows machines, press control and the keyboard's left arrow key.

Literature Cited

1. Burke, K. A.; Greenbowe, T. J.; Windschitl, M. A. J. Chem. Educ. 1998, 75, 1658.
2. Michel, R. G.; Cavallari, J. M.; Znamenskaia, E.; Yang, K. X.; Sun, T.; Bent, G. Spectrochim. Acta B: At. Spectrosc. 1999, 54, 1903.
3. Anderson, M. R. Spring 2001 ACS CONFCHEM, April-May 2001; Lecture Demonstrations in Chemistry on the World Wide Web; Demo 5 (accessed July 2001).
4. Sanger, M. J.; Phelps, A. J.; Fienhold, J. J. Chem. Educ. 2000, 77, 1517.
5. Lancashire, R. J. Anal. Chim. Acta 2000, 420, 239.
6. Gardner, T. Chem. Educator 1996, 1, 4, S1430-4171(96)04054-X.
7. Muybridge, E. Animals in Motion; Dover: New York, 1957.

Thomas G. Chasteen is in the Department of Chemistry at Sam Houston State University, Box 2117, Huntsville, TX 77341;chm_tgc@shsu.edu.

World Wide Web Addresses

Plug-ins and Software

Blackboard Inc.

Chime Home Page

QuickTime

RasMol Home Page

Shockwave Flash

Windows Media Player

Animation or Technical Image Sites

Organic Reactions Animations, Brigham Young University

Cornell Theory Center NIH Movie Gallery

Computers in Chemistry at Cabrillo College

The Chemist's Art Gallery

How Stuff Works, Two-Cycle Engine

Useful References for Designing Sites

Scientific American

NOVA

Sites Used to Teach Chemistry Discussed in This Article

Chemistry-Based Animations, Sam Houston State University

Antarctic Ozone Hole

Gas Chromatography

GC/MS

Hydride Generation Atomic Absorption Spectroscopy

Photoelectric Effect

X-ray Fluorescence Spectroscopy

Access date for all sites is May 2001, unless otherwise denoted.