Modellus software allows the user to build mathematical models and explore them as animations, graphs, and tables. The user must enter the equations that define the model, as well any initial values. Algebraic, differential, or iterative equations an be used. After the defining conditions are set, one can view the result of the model in a gaphical or tabular format. One can also animate the model by cycling through values of each variable in the model or manipulating variables by changing values on graphical switches.

Modellus is similar to a software package called Stella that might me familiar to early users of personal computers. As an example of Modellus’s capabilities, consider the equations that model the movement of a ball thrown into the air:

where (x, y) represents the position of the ball at time t; g, the acceleration due to gravity; and v_0x and v_0y, the initial velocity of the ball in the x- and y-directions, respectively. Modellus allows the user to set initial values for v_0x, v_0y, and g; create a window that gaphs relations from the model; and then animate the model. In this example, a graphic of a basketball can be used, and a freethrow simulation, complete with player and hoop, can be created.

In addition to the ability to set up and simulate models of your own choosing, the software includes a wide variety of written models and animations, or simulation windows, in which the user can explore phenomena in the areas of physics, chemistry, biology, economics, engineering, art, and mathematics.

Modellus is very easy to use and functions flawlessly. The prepackaged models are accurate and often very clever. The user’s manual is brief but sufficient.

The only weakness that I noticed involves the quality of the graphics that I printed—the equations in the model and the graphics in the animation window were not as sharp as they appeared to be on the computer screen. Activity sheets for guiding student explorations would have been very useful. Teachers will need to prepare their own written or verbal guides for students if Modellus is used as part of a lesson.

Modellus is an excellent tool for integrating mathematical models with applications in other fields. It will be as useful to science teachers as to those in mathematics, and I recommend it especially for teachers collaborating with colleagues in science. An accurate and useful "Product Tour" is available on the Modellus Web site at www.krev.com/ed/Pages/Products/Mod/modellus.html, as is a free, downloadable demonstration version of the software. If considering Modellus, potential users might wish to compare its features and performance with those of Stella, which is now in version 5.0 and is available in demonstration form at www.hps-inc.com/products/stella/details.html. — Ed Dickey, University of South Carolina, Columbia, SC 29208.

Pros: Easy-to-use modeling software with predefined examples and user-defined modeling capabilities.

Cons: Printouts lack the clarity of the screen display.

Standards:Encourages the integration of mathematics with other academic fields.

Recommend: Recommended for both mathematics and science teachers and teachers of integrated studies.