You might be surprised, but They Might Be Giants are at the height of their popularity right now. Just ask any 5-year-old you know.

"We're 25 years into being a band, and suddenly we became hot commodities," said John Linnell, one-half of the quirky pop-rock duo that has unexpectedly found itself with a parallel career peddling children's albums that sell nearly as much as their adult albums ever did.

That is why They Might Be Giants are performing two shows in the Salt Lake City area this weekend. They'll perform an "adult" show at The Depot Friday night and follow that with a Saturday afternoon family show at the Murray Theater, featuring material from their four children's albums.

The "adult" show doesn't mean the Brooklyn-based duo will perform a show called "They Might Be Naked." It's just that The Depot serves drinks, so only those 21 and older can attend.

John Flansburgh and Linnell began their band in 1982, but it was only after they released their most popular album, "Flood," in 1990 that the musicians got their "first inkling that there was a world of children out there," Linnell said. Two of the songs from "Flood," "Particle Man" and "Istanbul (Not Constantinople)," were adapted into cartoon music videos by Warner Bros. for "Tiny Toon Adventures," an animated show that ran from 1990 to 1995.

It's not hard to see why kids would be attracted to the latter song, with a tune you can't get out of your head and lyrics that teach a witty lesson at the same time:

Every gal in Constantinople

Lives in Istanbul, not Constantinople

So if you've a date in Constantinople

She'll be waiting in Istanbul

Even old New York was once New Amsterdam

Why they changed it I can't say

People just liked it better that way

In 1999, the band released "No!," its first album of material intended for kids that was an unexpected hit among adults, too. In 2005, the band released "Here Come the ABCs," and in 2008 they followed it with "Here Come the 123s"; in September of this year came "Here Comes Science," which had one of the highest chart debuts in They Might Be Giants history. Instead of songs about birdhouses in souls, the band crafted easy-to-comprehend (and, again: catchy) songs about cells, photosynthesis and why the sun shines. Take the song "Meet the Elements":

Iron is a metal, you see it every day

Oxygen, eventually, will make it rust away

Carbon in its ordinary form is coal

Crush it together, and diamonds are born

Come on come on and meet the elements

After "No!," the band found out it was established enough to venture into other projects. As important, the members learned as they wrote the new albums that "Wikipedia's not the best source of information," Linnell said.

"Here Come the ABCs" was a huge success, certified gold with sales of more than 500,000 units to date. After "Flood," it's now the band's second-highest seller.

Speaking of "Flood," tonight the band will play the entirety of that 43-minute, 19-song album to celebrate the 20th anniversary of its recording. "We're playing a lot of songs that normally are uninvited guests, but some really work in a live setting," Linnell said.

Another thing that only adults will see is The Guggenheim Grotto, a folk-pop acoustic duo from Ireland who first came to Utah to perform at this year's Sundance Film Festival. They aren't on the bill for the children's show.

Guggenheim Grotto singer Kevin May called They Might Be Giants "a great model for longevity." The group is still new to the music industry, evidenced by May's amusement that he got to meet R&B singer Montell Jordan at Sundance as well as an extra on "CSI."

The band's first album, "Waltzing Alone," is gradually garnering attention and record sales, so May has switched to using iPhones to help him write songs. It's not the first collaboration between The Guggenheim Grotto and iPhones. When the phones were first introduced, a song from the duo was available as a demo on models in American stores.

But May still had to buy an iPhone -- no freebies for him. "I am going to have some harsh words for Mr. Jobs," he joked.

dburger@sltrib.com