The Jatakas, or Birth-stories, are believed to have been first written around the 3rd century C.E. The stories, linked to to Theravade Buddhism, tell of the 550 lives of the Buddha, pre-enlightenment.
There's a deep truth in each tale, such as show kindness to animals and be honest and you will be rewarded for your honesty. Karma, what you send out will come back to you, is demonstrated in simplicity in every tale.
Both of my children have read a number of the Jatakas as part of their home schooling. They both love the stories and quickly grasp the moral of each tale.
Recommended books:
Twenty Jataka Tales by Noor Inayat Khan. Inner Traditions, 1985. ISBN: 0892813237
The Hungry Tigress: Buddhist Myths, Legends, and Jataka Tales by Rafe Martin. Yellow Moon Press, 1999. ISBN: 0938756524
The Monkey and the Crocodile: A Jataka Tale from India by Paul Galdone. Clarion Books; Reprint edition, 1987. ISBN: 0899195245
Etexts:
Jataka Tales by Ellen C. Babbitt (1912). http://www.sacred-texts.com/bud/jt/index.htm
More Jataka Tales by Ellen C. Babbitt. http://www.gutenberg.org/dirs/etext05/mrjtk10.txt
Jataka Lesson Plans
Haven't I Seen You Somewhere Before? http://edsitement.neh.gov/view_lesson_plan.asp?id=592