Graphing calculators were introduced about 25 years ago. (Sarah L. Voisin/The Washington Post)

It was once the go-to gizmo for high school math whizzes who prided themselves on their ability to turn complex equations into artsy graphs on a black-and-green screen.

But 25 years after the introduction of the graphing calculator, some think it’s starting to seem a little too old-school.

“Why should I spend $90 on something so outdated?” asked Eduardo Siguel, a father of two Montgomery County students who says he has been arguing with his kids about buying a graphing calculator. “I want my children to be able to use technology of their generation.”

Dozens of smartphone applications perform the same graphing functions, for the cost of a candy bar. In Prince George’s County, math teachers in some middle schools will experiment this year with using iPads instead of calculators, officials said. Fairfax County teachers also are exploring the idea. Montgomery has not looked into it because cellphones aren’t allowed in class, said Ed Nolan, the county’s math coordinator.

Officials in the three counties said they worry about turning to technology that could be just a fad — particularly when it’s not allowed on standardized tests such as the SAT.

In math education, there have long been twilight moments when one tool is eclipsed by another. But acceptance of those tools hardly ever comes easily, said Peggy Kidwell, a curator at the National Museum of American History who is an expert on the subject.

Twenty years ago, there were debates about whether calculators would ruin the discipline of learning arithmetic. Now, educators grapple with the idea that the same tool that allows disruptive, under-the-desk text messaging can actually facilitate learning.

Doug Mitchell, a math teacher at Nova High School in Seattle, has taken the jump. Frustrated that his school couldn’t afford traditional graphing calculators for all of his math students — some models cost $100 apiece or more — he encouraged students two years ago to start pulling out their phones. It worked. “I found that my students were actually getting calculus a little faster,” Mitchell said.

“It was just easier to understand,” said Levena Ostergaard, 16, one of Mitchell’s students, who uses an iPhone app called GraphCalc. “There were just fewer buttons, and it was easier to manage.”

Facing such competition, manufacturers are seeking strategies to prevent the graphing calculator from going the way of the abacus.

“We are in a modern-day calculator war,” said Greg Yurchuck, director of Casio America’s Marketing Education Division.

This year, Casio and competitor Texas Instruments are pushing new graphing calculators equipped with color screens and other features designed to preserve their place in schools.

Both companies understand that math tools come and go, based on the needs and expectations of the country. Slide rules were the gadget of choice for young math dynamos from the late 19th century through much of the 20th, until they were sidelined by pocket calculators in the 1970s. In 1986, Kidwell said, Casio brought the first graphing calculator, the fx-7000G, to the United States. (It had been introduced in Japan.)

By the mid-’90s, TI, which directed heavy promotions at teachers, dominated the market. Its TI-83 and TI-84 editions, still the most popular, appealed to fledgling student programmers. They could use coding to install bootleg versions of video games, such as the Mario series or a game similar to Pac-Man called Snake.

“High school was about finding and programming the wide world of games on your graphing calculator,” said William Bar­ratt, 26, a graduate of Thomas Jefferson High School for Science and Technology in Fairfax County who designs microchips. “It was a constant companion.”

Now, the same programmers who grew up with the graphing calculator are designing replacements. In 2008, Gabor Nagy of Austin produced a graphing calculator app for the iPod Touch. Nagy said there had been 1.4 million downloads of the versions of his app. He said that other developers have produced more than 60 similar apps.

Still, Nagy said there’s no way he can compete with the big calculator companies. TI and Casio have worked recently with teachers to produce a next-generation “handheld.” (The word “calculator,” TI says, is becoming outmoded.)

“Parents can’t buy a new handheld every year,’’ said Tysun McKay, senior marketing manager at TI. “We wanted to make sure that our products really offered something new and useful.”

This year, TI is marketing the Nspire CX, which graphs in 3-D and in color. Casio offers the Prizm, also with a color screen.

The companies are trying to appeal to the push for real-world examples in math education. For example, if a student takes a picture of his house, he can upload the photo to the next-generation calculator, place it on a graph and calculate the roof’s slope.

“I think the problem a lot of students have with calculus is they can’t see or visualize what they’re learning,” said Kamelia Zolfaghari, 16, a math- and science-loving senior at Eleanor Roosevelt High School in Greenbelt.

She said she would be interested in playing around with a new type of calculator or an iPhone. But she has one caveat: “I want to use what the teacher teaches with.”

Zolfaghari describes her TI-83 as “just a tool,” not much different from her pen or a protractor. When told that the graphing calculator was once considered about the coolest thing a math lover could have, she laughed.