The teens in Brian Cohen's math classes love to use SketchUp 8 for 3D modeling. They design their dream houses, then dive into the algebra and geometry problems their own imaginations create.

OK, so what's the surface area of the living room walls? How much would it cost to wallpaper them? How much air volume is there in the den? You have to know if you want to heat it.

SketchUp 8 runs smoothly on any of the 33 refurbished ThinkPads, circa 2010, that Cohen raised funds to buy for his classroom. But woe to the student who takes that math work into the school's computer lab, outfitted with Apple iMacs built when George W. Bush was in the White House - not so long ago in people years, but seriously aged in digi-time. On them, SketchUp 8 is too new to load.

That's just one small example of the challenges faced by Cohen and his students, and an illustration of the persistent disparities - the "digital divide" - that emerge yet again in a report due out Thursday from the Pew Internet and American Life Project.

Even at Cohen's school, an academic magnet so tuned to technology that its name - the Academy@Palumbo - looks like an e-mail address, talented students are weighed down by a lack of technological resources. And unlike their counterparts in schools such as Lower Merion High, where Cohen went, the academy's largely low-income students aren't likely to find better computers at home.

Pew's study is the latest in a series aimed at understanding how teens interact with a technology - the Internet - that in two decades has transformed their world. It looks at how their teachers use technology, both in and out of their classrooms.

Project director Kristen Purcell says Pew did not set out to focus on the well-documented digital divide when it surveyed nearly 2,500 sixth- to 12th-grade teachers. It was hoping to learn how they use a range of technologies and see their students using them, and also see how technology affects the educational process.

The divide leaped out anyway. Teachers of poorer kids were consistently less positive about technology's role, less likely to say schools provided key resources and training, and more likely to say students lacked home computers with Internet access.

In North and South Philadelphia, there is plenty of evidence of the problem - and of teachers fighting the tide.

Cohen, who does double duty as his school's technology coordinator, tries to promote Comcast's Internet Essentials, a $10-a-month program for low-income families. At last public count in September, Comcast had signed a paltry 3,250 customers in the Philadelphia market, even though it estimates that 98,000 families qualify in Philadelphia alone. A spokesman says Comcast will be reporting additional progress next week, but declined to provide details.

Cohen, 27, saw the other side of the gulf before leaving Lower Merion - a school that spends about twice as much per pupil as Philadelphia and provides every student with a laptop - for the University of Pennsylvania.

Those from such districts get a huge head start, he says. Lower Merion grads "know how to use all the tools they're going to need in their future world."

Mary Beth Hertz, technology teacher at North Philadelphia's Alliance for Progress Charter School, tries to get her kids going early. Kindergartners have technology class at least once a week. Fourth through eighth graders come to an iMac-outfitted lab about twice a week.

Hertz, 32 and an Oberlin College grad, sees some students shine, such as a seventh grader who "taught himself how to program because he wanted to hack into his video games." For this year's Computer Fair, she's mentoring five pupils creating things such as a website, an animation, and a graphic-design logo.

Only one had access to a computer and the Internet at home, Hertz says - echoing a finding of the Pew study's teachers, who said just 18 percent of students had access to all or nearly all the digital tools they needed at home.

Hertz is quick to say technology isn't everything. "It's great to have an interactive whiteboard in the classroom - people say, 'Woo-woo, technology,' but it's just a glorified chalkboard."

She says even affluent families face the problem that kids know more about being Web consumers - say, of Facebook - than about basics like file management.

Still, she's painfully aware her students will compete with those with far more resources - a reason she sympathizes with the argument that Internet access should be a basic human right. Without it, she says, we're "just widening the divide between the haves and the have-nots."

Contact Jeff Gelles at 215-854-2776 or