Practical Problems With CalculatorsThis page will collect comments from teachers on what they are observing about the use of calculators in math classes. We invite you to send your observations as well!
In an online math discussion group, an Iowa higher school teacher posted this reply to this earlier comment:
Though the district provided calculators this year, a number of Levittown students have owned their own since eighth grade. Over the years, they have learned to plot graphs, calculate exponents, check their computations as well as download games from the Internet.As a high school teacher, I find that most of my students have calculators, mostly TI-83 and higher numbers. I disagree with all of the above statements with regard to my students.
When a statement is made that "they have learned to plot graphs," I would qualify that to indicate that they (might) know how to punch in the equations on their calculators. However, I do not believe this is equivalent to students' understanding how to plot graphs. In fact, many of mine stare at me when I ask them to name three points on the graph of f(x) = e^(x+2) - 3. Worse, ask them to name three points on the graph of f(x) = ln(x+2) - 3. Ask them to find A and B if f(x) = Aln(x) + B if f(1) = 10 and f(e) = 1, and they stare helplessly at their calculators.
Ask them to compute the log (base 10) of the cube root of .01. Once again, their fingers itch for the calculator, and after consulting it, most would give an answer of -.67, typical of what I call a "calculator math" answer. The correct answer, of course, is -2/3, but most calculator-raised students are wild about rounding off all decimals to two places. To actually figure out the log (base 10) of the cube root of .01, much knowledge is necessary, including knowledge of place value (.01 is 1/100), knowledge of negative exponents (1/100 = 10^-2) and knowledge of equivalent radical and exponential expressions (the cube root of x is equivalent to x^(1/3)) and I am convinced that dependence on the calculator hinders the acquisition of such knowledge.
I assume that "calculate exponents" means something like taking 8 to the 6th power. But I have students in algebra 2 and precalculus who do not understand what 2^-1 means, and who do not know in their heads that 2^4 = 16 or that 4^3 = 64. They didn't bother to learn it, because they know the calculator can do it for them.
Regarding checking of computations, what a joke! My students don't want to check anything even when the calculator is staring at them! They want to ask me if their answers are right. I cannot get them to use the calculator when they ought to! I fear that it breeds lazy minds.
Finally, do not talk to me about games on the calculator. In the last week, I've had to confiscate two calculators and send pointed e-mail messages home to parents of kids who were playing tetris on their calculators during class. Both students are underachieving in my class, and playing calculator games during class does not do anything to remedy this situation.
I want so much to be able to let students use calculators responsibly, for computing compound interest problems, exponential decay problems, etc., and usually end up having to give two-part tests or quizzes, to make sure they do know how to use their calculators, but to also guarantee that they understand the meaning of log(base 10) of a number like 10000.
Most of these pricey calculators are very easy places to store textual information, definitions, and formulas. I have students who have programmed the quadratic formula and numerous other kinds of formulas and theorems into their calculators. It makes it very difficult for me to assess what they really know when they can cheat so easily.
A posting on an education discussion list: