Voices rang out from the Dartmouth Middle School auditorium. Inside, approximately 130 sixth graders hemmed in around choral director Tara Thomas and her center-stage piano. She had one hour left to get a smooth rehearsal from her preteen students before the winter concert on December 15.

“We have 20 minutes left. I don’t have time for questions right now unless somebody’s bleeding,” said Thomas, racing the end-of-day school bell the day before. Somebody was bleeding.

The sixth grade students’ winter concert was one of three concerts scheduled for the week, leaving Thomas with the task of training changing voices, enforcing single-file lines, and perfecting light choreography for about 400 students. But Thomas’ 19 years of experience in middle school music (12 in Dartmouth; seven in Acushnet) make her more than ready for the task.

“I’m pretty excited about our last piece, ‘Jingle Bell Sleigh Ride,’” said Thomas, explaining the mix of “Jingle Bells” and “Over the River and Through the Woods.” The performances include Christmas mashups, Hanukkah tunes, and winter jingles. “I just hope they don’t forget the words,” she said.

The sixth, seventh, and eighth grade classes started practicing in October, but the real challenge is that Thomas only sees each class twice every six days due to a rotating schedule, she said.

“With Thanksgiving, assemblies, and picture days, it’s really tough for them,” she said about the schedule interruptions. But on the night of the concert, it all comes together, she said. A month before their winter concerts, students start to memorize the music.

“You can just really see how proud they are of what they did, and the parents are all excited,” said Thomas.

Despite any “attitude” and “eye rolling” during rehearsal, the eighth graders’ December 12 concert went terrifically, said Thomas.

“Most of the boys still sing very high in the sixth grade. Last night was very exciting because they sang in three parts,” she said, explaining that there’s more of a tenor and bass section as the students mature. It’s still small though, so she combines the deeper parts, and plays them in harmony with an alto and soprano section.

“It’s cool because they can do so much more than elementary school kids,” said Thomas, who is a vocalist and pianist herself. She explained that elementary school students typically sing in unison. She introduces different parts in sixth grade, and works up to the three or four different parts by eighth grade.

“I definitely mix it up every year because if I had to do the same songs, I’d go nuts,” laughed Thomas.

The seventh graders’ winter concert is on December 14 at 7 p.m. in the middle school auditorium. The sixth graders’ concert is on December 15, same place and time.

Attendees are asked to make a $1 donation to help support the school’s music department.