Mandy Brigham is delighted to see her former pupil Billie Eilish succeed as a musician.

Following her emotional shout-out to Brigham in her 2024 Oscar victory speech, Eilish, a former Los Angeles Children’s Chorus teacher, is thinking back on her time as a student with the “What Was I Made For?” superstar.

“I remember Billie from her first day of chorus quite well. Brigham tells PEOPLE, “I remember exactly where she was sitting, and I remember she was sitting up really straight.” “Everyone’s pretty quiet at the first rehearsal because no one comes in knowing anyone else, but she was just really tuned into what was going on.”

Brigham directed both young and intermediate groups of singers at the Los Angeles Children’s Chorus for 22 years until leaving after the 2022–2023 season. She first taught Billie’s older brother Finneas, who she assisted in getting ready for an opera at Santa Monica College while he was a student of hers, and via that relationship she got to know the O’Connell family.

Brigham was aware that Billie was from a musical family because he had already met Finneas and their parents, Maggie and Patrick, and he saw the future Grammy winner right away. The retiree remarks, “I just realized how much she loves to sing as I got to know her.” “She always sang beautifully in tune, which is a gift to a choir director because you can place that person somewhere and know that others will follow their lead.”

Throughout Billie’s four years of instruction with Brigham, the young performer’s passion in songwriting became apparent to her. “I saw her creativity at a young age. She remembers, “She is really her own person.” “When she was a little bit older, she would have a notebook, and she would jot down ideas for lyrics and stuff.”

Billie’s stint with the LACC ended when Brigham’s choir went on foreign tours to British Columbia and Japan. The artist had published early tracks like “Six Feet Under” and “Ocean Eyes,” which were becoming popular online, by the time of the later tour. The teacher explains, “Everyone was excited, and we were all aware of that.”

Billie has maintained a connection to her heritage even after becoming well-known. She featured the LACC in her Disney+ concert special Happier Than Ever: A Love Letter To Los Angeles and surprised the young performers with a visit while they worked on the project at Capitol Records’ studio in L.A. “She was so incredibly kind to them, giving out hugs and all that sort of thing,” Brigham recalls. “I think that was very, very special and memorable for them.”

Even prior to addressing Brigham at the Oscars, the “Bad Guy” singer continued to acknowledge the significance of her relationship with the man. “When I retired last year, there was a tribute video made,” she explains. “Billie, Finneas and Maggie all recorded a little, I guess, ‘thank you’ to me, and it meant a lot to me.”

The “Happier Than Ever” hitmaker has had a significant influence on subsequent LACC members as well. “They get really excited about Billie being in the choir,” says Brigham. Each year at auditions, we ask them, ‘Well, how did you find out about the chorus?’ “Well, Billie Eilish was in it,” they remarked.

Billie then mentioned the teacher while accepting Best Original Song for her Barbie soundtrack hit “What Was I Made For?” at the Oscars earlier this month. Brigham was at the Indian Wells Masters Tennis Tournament. Brigham always watches the awards event. “Then, all of a sudden my phone exploded,” she says. “I think disbelief would be the best way to describe how I was feeling.”

While the LACC has many alumni who’ve gone on to become successful in opera and classical music, Billie is certainly the biggest star to come from the organization — which Brigham says is a testament to its teachers’ approaches.

“Our goal is to train the singers so that they can sing beautifully and with a really healthy technique no matter what kind of music they decide to sing,” she says, adding that “it’s worked really well” for Billie.

Getting mentioned on stage at the Oscars isn’t the kind of recognition a teacher like Brigham necessarily expects, but she says the moment felt “amazing.”

“As a teacher, when you hear that a student knows you believed in them, that’s really a gift,” she says. “Your hope as a teacher is to just let students know that you believe in them and to help empower them to pursue their dreams and develop their gifts. And so to have that affirmation was very special.”