vs. 34% for the comparison group). On transformation tasks involving equation solving and expression simplification without any context and for which calculators were not permitted, however, the comparison group scored higher (38% correct vs. 29%). This finding did not surprise the researchers because the new curriculum had not emphasized symbolic manipulation with paper and pencil, whereas the curriculum for the comparison group had consisted almost exclusively of such manipulation. In fact, when the equation-solving tasks were presented in a contextualized form, such as the example shown in Box 8–5, the students in the new curriculum were more successful than the comparison students (61% correct vs. 45%).51

The ways that graphing calculator use can produce improved student performance were examined more deeply in a recent study.52 The study used a three-condition pretest-posttest design to study the impact of prolonged use of the graphing calculator throughout the entire school year for all topics of the mathematics curriculum (i.e., functions and graphs, change, exponential and periodic functions). Three experimental classes used the graphing calculator throughout the year; a second set of five experimental classes used the graphing calculator with only one topic for six weeks; and four classes, which served as the control group, covered the same subject matter throughout the year but without the graphing calculator. The students who used the calculator throughout the year had enriched solution reper

Box 8–5 Water Business Problem

The Turtle Mountain Springs Company made plans for growth in its share of the water business. They predicted that annual income from the sale of its bottled water B and filters F would change over time according to the following formulas. Time, t, is in years since 1990, and income is in millions of dollars per year.

Bottled Water Income: B=20+5t

Filtering Devices Income: F=28+3t

Question: When does the Turtle Mountain Springs Company expect the two water products to give the same annual income?

SOURCE: Huntley, Rasmussen, Villarubi, Sangtong, and Fey, 2000, p. 347. Used by permission of the author.

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