A teacher talks with her students, Sept 18, 2014. [Photo by Chen Bei/chinadaily.com.cn]

She looked sad and tearful when asked about her daughters' impairments, declining to say more than they had "delayed mental development."

About a quarter of Pengcheng students are diagnosed with autism, while others have cerebral palsy, Down's syndrome, Phenylketonuria and certain disabilities that defy medical terminology.

"The symptoms they show are varied, but most have problems with reasoning, cognitive learning, depth perception and social communication abilities," said Wang Juan, a math teacher in the school for nearly 10 years.

Autistic children have relatively higher self-care abilities and do better with numbers than other students, according to Wang, but they are almost oblivious to the outside world.

"Those suffering other disabilities at this school, with IQs scored below 50 on average, need to take longer to learn basic knowledge," she said, adding the IQ – or "intelligence quota" was a term coined by psychologist William Stern – is internationally regarded to be functional in the 70-to-130 range.

"But every child is able to learn," Wang said as she showed off her students' work, including paper cut-outs and hand-woven scarves. She said with pride that some of her students could do math equivalent to their 7th grade peers at public schools.

This ability to learn, and finding a place to nurture it, is what allows parents like Luo to sleep at night, knowing she may have a happier dream rather than the heart-rending ones of the past.

"I also have another dream that occurs again and again," Luo said.

In the dream, she and her son are aboard a train bound for someplace far away. The son is quietly playing alone as usual, but suddenly he raises his head, gazes at her and says, "Mommy, I love you!"

"I will keep in mind forever his sparkling eyes and sweet voice at that moment. His eyes and voice tell how he feels and shows love," Luo said.

"If someday this dream comes true, I would be the happiest mother in the world."