THERE'S A GIANT guitar for aspiring musicians to strum 12-foot-long strings.

There's a soundproof karaoke studio for budding singers to strut their vocal stuff behind the microphone.

There's a place for up-and-coming conductors to take their turn leading an orchestra through a contemporary classic or sensational standard.

Welcome to Mostly Music, a 6,000-square-foot interactive exhibit at the Maryland Science Center at Baltimore's Inner Harbor that takes children inside the world of music and offers them a glimpse of the mechanics that go into making it.

The exhibit presents a smorgasbord of sensations, providing children with fun and entertaining activities while teaching them everything from how music is made to music history to musical traditions in faraway places.

There are classic instruments like piano and violin, and more exotic offerings like a conga drum and a marimba. Children flocked around the more unusual instruments on a recent Sunday afternoon, giggling with pleasure as they banged a kettle drum and clanged smaller percussion instruments.

"Wow!" one child after another exclaimed as they peered skyward at the 14-foot acoustic guitar, the hands-down hit of the exhibit.

Children's eyes widened as they approached the wooden structure, whose open sides invited visitors to explore its internal mechanisms. A hand print on the side gave children a place to feel the vibrations caused when the strings were strummed. Children ran in and out, listening for differences in the sound emanating from the inside and outside of the guitar.

Another favorite was the karaoke studio, where singers, typically siblings or a parent and child, stood at two microphones and warbled, following the lyrics on a television screen illustrated with cartoons and other images. I had to promise my son an ice cream cone to dislodge him from the microphone after repeated renditions of "Old MacDonald Had a Farm" and "New York, New York."

Here's a helpful hint: Do the karaoke early. We did it before 1 p.m. and had it to ourselves for more than 15 minutes. But later in the day the studio became so busy that some families had to wait for several minutes to get inside.

Mostly Music was created at the Pacific Science Center in Seattle to allow children the opportunity to experience such scientific components of music-making as how hollow places amplify sounds and how different amounts of stress on strings create different sounds.

The exhibit has four areas, including the Center Stage, where demonstrations were conducted throughout the day on how music is made. Children and grown-ups are allowed to take the stage to perform with acoustic and electric instruments. Small children performed with less complicated instruments like blocks and sticks.

The giant guitar is the centerpiece of the Music Lab, which also features many different instruments to help children discern how sound travels and the correlation between sound and shape.

In the World Club, visitors listen to music from foreign lands on the World Jukebox, which features tunes ranging from folk to rap from, as the center's literature says, "Albania to Zambia." There are reggae selections from the Caribbean and instrumental pieces from Asia, all available at the touch of a tiny finger. The wall is lined with photos of unusual instruments being played in their native countries, like an Irish frame drum, Bolivian panpipes and a Nigerian double-headed barrel drum.

The Conservatory gives classically inclined visitors an opportunity to compose their own songs on a computer and learn about classical composers and their work.

At the edge of the Conservatory, young conductors gazed at instructions explaining how to conduct an orchestra to different tempos as they waved batons to and fro, mumbling "dum-dum-de-dum" and leading imaginary musicians through classical tunes.

Mostly Music also features a special display on Baltimore music legends in a joint project between the Maryland Science Center and the Johns Hopkins University Peabody Conservatory of Music, also located in Charm City.

Titled "Baltimore Beat: An African-American Musical Heritage," the exhibit spotlights Baltimoreans who went on to fame and fortune as musicians. Part of the display highlights eight local-born musicians, including Cab Calloway, Eubie Blake and Billie Holiday, and chronicles musical life for blacks in Maryland from emancipation to the civil rights movement, complete with pictures. At a touch of a button, visitors are treated to the rich, smoky tones of Holiday, the lilting fun of Calloway and the music of other artists in the display.

Maryland Science Center exhibits director Stephanie Radcliffe calls the display "a history lesson of sorts," where visitors learn "more about the `stride' style of piano playing, ragtime and the birth of jazz. And the stories of the musical legends paint a poignant picture of how times have changed."

Mostly Music is one exhibit in a building full of family-oriented exhibits geared to combining science and fun in interactive activities for children of all ages.

There are many fun and educational things to play with, like a giant water vortex where children see the formation of a funnel when they turn a handle on a cylindrical water tank. The center's IMAX theater is currently showing "Olympic Glory," which captures the pageantry of the XVIII Winter Olympic Games while offering insight into the personal lives of athletes.

Be warned -- children love the Science Center. Allow ample time to browse and let them explore all the different activities at the three-level facility. It's easy to make a full day of it.

MOSTLY MUSIC -- Through Feb. 3 at the Maryland Science Center, 601 Light St., Baltimore, about 55 miles from downtown Washington. 410/685-5225. Web site: Take Interstate 395 north to Baltimore and take the Inner Harbor exit. Turn right on Light Street to the center. Open daily, Monday through Friday 10 to 5, weekends 10 to 6. Ages 13 and over $10.50, seniors 60 and over $9, $7.50 children 4 to 12, free for children 3 and under. There is a Friendly's Express restaurant and ice cream store on-site.

Also on exhibit at the Maryland Science Center:

Rocks in Space: Visitors are treated to a planetarium exhibit featuring asteroids, comets and meteors.

Outer Space Place: Catch the planetarium show, then venture outside where young visitors are invited to don astronaut jumpsuits, learn about space on computers, create their own robot with the help of Matt the scientist or maneuver a space rover over a rendition of the surface of Mars and watch it on television.

Dino Digs: Aspiring paleontologists are given little eye protectors, brushes, shovels and other tools and invited to chip away at the ground covering buried "dinosaur bones." A photographic mural on the wall depicts a recent excursion for dinosaur remains in Texas. One of the people in the mural, science center scientist Lee Billingsley was present the day we visited and delighted children at the exhibit with his knowledge of dinosaurs and information about books and activities to foster children's interest in paleontology.

K.I.D.S. Room: This activity room on the top floor of the center features play equipment for younger children, but be aware that it closes, unannounced, a half-hour before the other exhibit areas.