"We have all kinds of intelligence levels in this class," says Meredith. She coaches all 24 kids individually, keeping track of raised hands and helping each one in turn. Despite the noise, she seems to notice every note.
With a piercing whistle, she stops the class. In the silence, she gives quick corrections such as, "Kelly, you started on an F and not an E." She starts them again, keeping time by clapping paper.
Sitting at a Steinway, senior Kira Pugh seems frustrated. She plays the melody with her right hand, but her left hand fumbles between chords.
Meredith covers the student's hands with her own, guiding the fingers.
"I can't see!" complains Pugh.
Meredith asks Pugh to use a slower tempo and the student manages to finish.
"Every time I come over here, you say, 'I can't do this,' and then you do it," Meredith says. "I quit!" says the student.
"You never quit," says the teacher, moving on.
Pugh smiles. "I don't talk to other teachers but her," she says. "Everybody else knows me as a 'bad attitude,' but she's the only one who ever talks talks to me. Plus, she's goofy."
Meredith never meant to teach or come to Hagerstown. Born in Fairmont, W.Va., she moved to Silver Spring, Md., attended Springbrook High School and went to the University of Maryland in College Park.
"I never wanted to be a teacher," she said. "I wanted to major in sociology and change the world." Her first class on the subject changed her mind.
"I thought it was the most boring class I'd ever taken in my life," she said.
Music education was a natural. Everyone in Meredith's family played piano and her father sang. She played trumpet and French horn in high school band. She sang in the school and church choir.
Piano involved too much practice, so she chose vocal studies. "Things just happen," Meredith said. If the Washington County School System hadn't offered her a job first, she might have moved to Prince George's County.
"I was afraid I wouldn't get a job," she said.
She got her bachelor's degree in education and started working at Washington Street School (now Western Heights Middle School) in 1972. She remained there until fall 1982, when she came to South High. Two years later she got a master's degree.
Music is important to her. It's one of civilization's most important assets, she said, adding, "If we don't have a love of the arts, where is our humanity?"
The students say they like her sense of humor and personality. "We love her because she's awesome," said freshman Tonya Cantrell. "She's down to earth and she helps us learn."
Meredith's students give annual shows, such as the Fall Fest and holiday and spring concerts. Last year, the teacher took her students to sing at businesses in the community such as Weis, Prime Outlets and Ravenwood.
"I like to do something different, often," she said.
She takes her students to New York each year to see a Broadway show. She helps organize musicals, such as "Oliver," "Music Man" and "Carnival." Photographs from the shows and souvenir sweatshirts hang on her classroom walls.
The teacher also gives general life lessons, such as the signs of advice on the walls. "Be nice," reads one, along with, "Save $ with your first job" and "Plan life like you'll live forever."
Meredith has a humble opinion of herself. "I have never claimed to be a good teacher," she said. "I communicate relatively well with the students. I like kids, and I think I'm still 18."
She makes a point of reaching students with humor, letting them know laughter is allowed. In 1997, she organized a faculty show and used the profits to create the Live and Laugh scholarship, $500 given to students annually.
Teens are often stressed out with peer pressure or afraid of making mistakes, Meredith said. She teaches them to support and respect each other. She also shows them compassion.
"If they know we care about them, they're fine," she said.