What a wonderful and huge topic you bring up! Nearly every religion and culture has its creation stories and many of these are oriented towards being accessible, or even entertaining, to young people and yet they also grow with us. Whether the origin of the universe and the origin of life occur in the same action or even story varies by culture. Although the stories are as diverse as the cultures they come from, stories about the beginning of existence seem to be universal. You can probably find books about creation stories in public libraries but if available, I would recommend searching the web and/or having your students search the internet under key terms such as "creation myths" or "creation stories". I'll include some sites that I found here but, as with anything on the web, I can't guarantee their accuracy or scholarliness.

Here is a site designed for English teachers and has some resources on creation stories.

creation

Good luck with this interesting topic!

Here are some good books:

The Big Bang, by Joseph Silk - talks about the origin of the universe.

Atom, by Lawrence Krauss - talks about the origin and history of the universe and the origin of life, from the point of view of an oxygen atom.

The NASA Origins program also has a lot of contemporary information on cosmology, astrobiology, and the origins of life/the universe:

origins

Here's an extensive listing of archaeoastronomy websites, where you're sure to get some information on ancient people's ideas of cosmogenesis:

archaeo