On stage, a choir of 30 had finished three songs in Chinese and English. The conductor, a devoted woman in her 50s, had every reason to be proud of her students across the grades and octaves - and the globe, as this is an international school.
The final show came as a pleasant surprise. Four teenage girls wearing Tibetan long dresses with rainbow-colored aprons danced to a lively song. They came from the school for orphans and homeless children called Beijing Guang'ai (Light and Love) Children's Home, for which this charity event was held.
We didn't see any children from Guang'ai at last year's event. It was good to finally see them, and they danced with such talent.
Guang'ai's founder Shi Qinghua thanked the children, parents and teachers at the end of the show. Over the past decade, he had provided hundreds of homeless children with shelter, food and basic education.
He had had to move the school many times, and he spent most of his time seeking support, teachers and vocational schools so the older children could become independent.
As we lingered in the mall and debated which kind of pizza to order, I couldn't get my mind off the four girls and their haggard headmaster.
Would they have a hot meal that night? Would the nearly 100 children at Guang'ai have enough heating to get through this long, cruel winter?
The weekend event collected some 88,500 yuan by selling more than 870 postcards, 500 New Year paintings and 600 balloons, the school says.
This might not be much, but I believe my son and his classmates will walk into the New Year with memories of not only performing a popular song but also doing something much more important.
Beijing style: Duck, opera, fog and cough...