Explore Tibet by Evers, Heller, Ramirez, Reid, and Romano: published by Snow Lion Publications and The Newark Museum. This is aimed at young children, has recipes, etc.
Learning from the Dalai Lama by Pandell: published by Dutton Children's Books.
The 14th Dalai Lama by Steward, published by Lerner. This is for older children, probably 5th grade and up.
Symbols of Tibetan Buddhism by Levenson, published by Assouline. This is an adult book, but may be useful.
The Dalai Lama by Demi: published by Henry Holt. (A picture book biography of the Dalai Lama.)
The Little Lama of Tibet, Raimondo, Scholastic
Fiction (These are all picture books suitable for elementary age):
All the Way to Lhasa by Barbara Berger: published by Philomel (for younger elementary grades)
Tibet Through the Red Box by Peter Sis: published by Farrar Straus Giroux (Fascinating, sort of fiction and non-fiction - for older elementary grades)
Tenzin's Deer by Barbara Soros: published by Barefoot (A sweet Tibetan tale)