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What would you do if you had TI92's?
Posted:
Feb 18, 1998 12:13 AM


This is prompted by an email that I received.
I mentioned that our math dept. had just purchased 20 TI92's plus a viewer. These are supposed to be for all math teachers in our dept. to use. I most easily can envision the geometry teachers (of which I am one) using the Cabri/Geometer's Sketchpad like application. (I also have access to a computer lab with 13 computers running Geometer's Sketchpad and have taken my Geometry class in about 4 or 5 times so far this school year.) But, for Calculus...what would one use the TI92 for? I wanted to use them to "discover" the chain rule, but we didn't get the calculators until we were long past that. I thought, I could have the students use the symbolic manipulation part to help with the following problem: Given: f(x) = sqrt(x^22x) g(x) = sqrt(x) h(x) = x^22x First, express f(x) as a composition of g(x) and h(x). Second, find f'(x), g'(x) and h'(x). Express f'(x) in terms of g, h, and their derivatives. [ the TI92 I envisioned being used for finding f'(x). I did have my students do this without the TI92. They had to use the definition of the derivative to find f'(x) since we didn't have the chain rule yet, and were trying to discover it.)
I only assigned them a very few problems of this type over a few days. With the TI92 they could do the derivative of f(x) on the Calculator, and many more such examples without the tedium of cranking through the definition of the derivative and hopefully begin to recognize the pattern themselves.
Of course, my students all own their own TI82 or 83. So, I would like to use the 92's for something they can't do on their 82s or 83s. To me, that means symbolic manipulation or things with the Geometry construction application. I have some ideas that it might be useful with constructing tangents that one can drag and maintain the tangency, but I haven't had enough time to try that out yet and see how it works. Anyhow, we're long past that, too (for this year). Here is a call for all ideas that you might have for using the TI92s to teach AP Calculus. Sheila King



