# A MATH STUDENT'S BEST FRIEND

How to pick the right graphing calculator for your high school number cruncher

One of the stranger items in my house is an eight-foot-long working model of a slide rule rescued from the demolition of a high school. Devices like it once graced thousands of math classrooms. But no more. In today's math class, the slide rule has been replaced by the graphing calculator. And while the slide rule was a mathematical curiosity that few students ever learned to use effectively, the graphing calculator has won a place in every math student's backpack. Entire courses are based on the devices. Their use is encouraged on the SAT and SAT-II college entrance tests and required for the calculus advanced-placement exam.

REAL-WORLD. If you have a high-school student who's taking a course beyond first-year algebra, a graphing calculator should be near the top of your back-to-school list. In addition to traditional calculator functions, it can take an equation such as y=x2+2x+3 and display a graph and a table of values. You can zoom in and out on the graph and use the cursor to find the coordinates of any point.

Teachers have taken these abilities and rebuilt the math curriculum around them. These revised courses, based on National Council of Teachers of Mathematics guidelines that encourage calculator use at all grade levels, emphasize using math in real-world situations and, especially, using calculators to collect and analyze experimental data.

Although some schools supply calculators for classroom use, most students will want one of their own. There's a pro-fusion of models, with prices ranging from about \$70 to nearly \$200, but choosing one is easier than it may seem.

First, find out if the school has a preference in calculators. Most do, and nearly always it's for Texas Instruments. Although perfectly fine calculators are sold by Sharp, Casio, and Hewlett-Packard, seven years of carefully built relationships with educators and textbook authors has given TI a lock on the market. Teachers are most likely to use TIs in classroom demonstrations.

TI currently offers seven models, but only two make sense for most students. The stripped-down TI-80 hasn't found much of a market, while the TI-81, TI-82, and TI-85 are obsolete units kept in the catalog for schools that have standardized on them.

IDEAL. For most college-prep students, the TI-83 (about \$95) is the calculator of choice. Its advanced statistical functions and easy-to-use data tables make it ideal for the new math curriculum. Students who plan to take courses beyond first-year calculus might consider the \$120 TI-86, which can handle differential equations. But its power comes at a price in user-friendliness, and students who don't need the extra functions are better off without them. The TI-92 is a \$170 marvel that can do symbolic algebra, but it would be most useful in a class built around its abilities. It's also not permitted for standardized tests.

The one non-TI calculator I would consider is the \$85 HP 38G. HP's technical calculators such as the 48G have long set the standard for both power and mind-boggling complexity, but I found the 38G at least as easy to use as the TI offering. If a school hasn't standardized on TIs, it would be a good choice.

Educators debate whether these calculators have made it easier for students to grasp tough math concepts. But the devices certainly have relieved math of much of its drudgery. Choosing the right one is a great investment in any student's future.

BY STEPHEN H. WILDSTROM

Updated Aug. 28, 1997 by bwwebmaster