Shi Qian, a 42-year-old mother, found an unforgettable memento for her teenage daughter, one that she hopes will teach a profound lesson.

It was a notebook recovered from the ruins of a collapsed school in Beichuan, where more than 1,300 students and school staff were buried or killed after the May 12 earthquake.

"My heart sank when I saw the notebook. It couldn't be more familiar," said Shi, who is among the many volunteers helping in China's quake zone.

Shi's 14-year-old daughter is a seventh-grade student in Beijing, and such notebooks are part of her daily routine.

The book was crumpled and dirty. On the white cover, in black ink, were the details of the owner: "Grade: Seventh, 2008. Name: Chen Xun. Student Number: 149. Instructor: Teacher Yang." Inside the book were three pages of geometry exercises, and the teacher's comments were written in red ink. Shi said it was picked up from the rubble, along with keys, school-bags and books stained with blood.

Chen Xun, the boy who once owned the book, isn't on the latest lists of survivors.

The 8.0-magnitude earthquake, the strongest in decades, has killed more than 50,000 people and left more than 5 million homeless.