Computer-Asslsted Blackboard L. J. Soltzberg. Houghton Mifflin, 1 Beacon Street, Boston, MA 02108 Hardware: Apple II family Components: 8 disks and instructor's manual Level and Subject: high school or college: lecture aids for general chemistry Cost: $50 per disk
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Summary Ratlngs: category Ease of Use: Subject Manw Content: Pedagogic Value: Student Reaction:
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Leonard Soltzherg's Computer-Assisted Blackboard (CAB) is an eight-disk set of programs designed to help a lecturer illustrate t h e following topics from general chemistry: gas laws, the Rutherford atomic model, quantization in a Bohr atom, wavefunctions and orbitals, heat and changes in state, kinetics and simple reaction mechanisms, equilibrium, and acid-base reactions, and titratians. Most feature a very high degree of interactive control of the output to a computer monitor analogous t o what one can do with a chalkboard. CAB provides quick drawing and erasure capabilities, a degree of animation, and (for some modules) the ability t o produce simultaneous changes in several parts of the screen image. I t would he useful for instruction in high school or college chemistry. The content of some modules is appropriate far physics instruction, as well. In the 32-page manual an introduction describes hardware needs, details of setup far various configurations far the Apple, options for display, and what t o do if the program crashes. Each module is amply described in its own separate section, which includes setup details, a verbal description of what the software produces on the monitor, and several suggested appropriate uses, emphasizing realistic and productive scenarios in the classroom. The documentation is complete, warns of pitfalls inherent in the software, and is well written. Even persons inexperienced with computers should be able to set up the necessary hardware and operate the modules by consulting the introductory section of the manual.
T h e manual needs more information about viewing devices. A monochrome monitor provides much crisper images than a color monitor, although for one module color is especially nice to have. The minimum suggested size (13 in.) is too small t o provide good classroom visibility for most of the modules. Best would he a high-quality color monitor of larger format, especially if more than 20students are toview it. The intricate character of some of the images makes the use of a large-screen video projector or multiple monitors essential for classes larger than 30. The programs follow a similar format and are easy to use. Most chemistry teachers should be able t o operate the software independently after a careful reading of one module's instructionsand half an hour of interaction with it. The remaining modules could probably he used successfully with only a cursory reading of the pertinent manual section. Each module features a first screen of menu commands and options designed to draw, activate, or erase text and images of objects which appear on an alternate screen (the "hlackboard"). The commands can be activated when either screen is visible. One toggles back and forth between the two screens with the space bar until the image aooears as desired. At first it is cumbersome .. 10have rhr menu options inviiihle while the blackboard ir vi*il,lr. H o a t w r , after 1; m:nutcs or so, most users s h d d he able to remember the mnemonic command designations and use the image screen as if it were a real blackboard. This writer could find no significant errors in content. Student reaction to the modules is reasonablv favorable. Thev feel the interactive tnuturc of CAB gives them a h m e r mrnrnl picrurr with s u m rnudulci. \ \ ' ~ t hothers, however, the greater speed of image creation (than with chalk) can he a disadvantage: it is very easy for the lecturer to produce images far faster than they can write them down. Therefore, the modules of greatest pedagogical value are those featuring a visual description of one of the physical models chemists use to explain how atoms and molecules operate. For example, the Bohr atom module allows one to depict simultaneously a Bohr model of the hydrogen atom (with electron a t any quantum level from n = 1to n = 5 ) , a simple electron energy level diagram, and an initially blank display of the line spectrum of hydrogen. An electron initially in a higher quantum level can be al-
lowed to fall to a lower quantum level. As that occurs, a squiggly arrow of the appropriate color (to represent a photon of light) leaves the atom, the appropriately colored line appears in the line spectrum, and the energy level diagram changes for the electron. (Ultravioletand infraredemissionsappear on the spectrum display as dashed blue and red lines, respectively, to simulate light invisible to the eye.) By allowing the electron to fall from successively higher levels, one can generate an entire emission series interactively and display it on screen. In contrast, with an ordinary blackboard or overhead projector and ordinary timing, the student must "marry" in his or her head the successive images drawn with the (sometimes) simultaneous verbal description of the lecturer. Experienced teachers of introductory chemistry are aware of the several incorrect ways a student can "remember" the way in which light is produced by excited atoms. This tool ensures that a student really sees electron energy CHANGES as intrinsically connected to the energy of photons emitted. It significantly enhances the presentation of this concept in a way that only a computing device could, mainly because i t is under the flexible control of the teacher, who can use hisher sense of timing and "feel" for how the concept is being understood to manipulate the Bohr demonstrator. This module is one of the hest uses of a computer for introductory chemistry instruction I have seen. It is certainly directed a t one of the most important concepts needed to understand the structure of the atom. I plan to use it in my courses from now on to introduce and explain atomic spectra, in conjunction with mare elaborate and visually appealing demonstrations of actual spectra. The others I plan to use include: Wavefunctions and orbitals. which can show clearly, for exampl~,how 3s. 31). and 3d d , i t a i i i u many-rlrcrronntomainrer~lig1tate t o remove the degeneracy present in a single-electron atom. A disadvantage of the multiple displays of radial probability produced is that they are not in different colors, making it difficult to distinguish overlapping plots. ~~~~
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Gas laws, for its ability to show simultaneously a gas expanding (or contracting) in response to a temperature change and the developing plot of volume versus tem(Continued on page A136)
Reviewed in This Issue
Reviewer Computer Learning Package J. D. Kruger
L. J. Solzberg, Computer-Assisted Blackboard Titles of Interest
Volume 64
Number 5
A135
May 1987
A135
perature. Student response to this module was only lukewarm, perhaps because the image of the plot is very small. Rutherford atomic model, which shows the results of the scattering of alpha particles off gold foil (through a visual track of the articles and an accumulating counter disolav, of aneles of deflection from 0 ' to IanO,.Thccratteringmn Iwshrnmun the snme rcrccn \\ilh n display of rhr nurl~ar mc,del uird to interpret the w t r e r l n a Heat and changes of state, for the ability t o show repetitively changes in physical farm of a solid, or liquid as it is heated or cooled simultaneously with the heating curve. This is useful AFTER my students have performed a similar experiment in laborstow.
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dice changes in coneen
