The Constellations and Their Stars - A good reference site for different constellations.  Most appropriate for teacher reference.

Astronomy.Com - Includes a section for kids, as well as a teacher section.

StarChild - This link will take you directly to their page on stars.

Stars - Sophisticated information, but good pictures of different constellations.

The Constellations - Gives information on the mythology behind the constellations with pictures outlining the actual formations.

Astronomy for Kids - Great site for simple pictures and descriptions of the constellations, plus information on the stars.

Match the Constellation - An online matching game.

The Stars by Patrick Moore.  A basic book of stars and constellations.

Where's the Big Dipper? by Sidney Rosen.  The history of constellations and how to find them on your own.

Our Stars by Anne Rockwell.  A good, basic book of star and constellation information.

Stars by Jennifer Dussling.  An easy to read star book.

The Magic School Bus Sees Stars, Scholastic.  Ms. Frizzle and her class journey into space to learn all about stars.

Constellations: A True Book by Paul P. Sipiera.  Best used as a reference book.

How the Stars Fell into the Sky: A Navajo Legend by Jerrie Oughton.  The story of "First Woman" and "Coyote" putting stars into the sky.

Stars and Galaxies: Looking Beyond the Solar System by Miquel Perez.  Informational book on stars.

Coyote Places the Stars by Harriet Peck Taylor.  A Native American legend on the beginnings of constellations.

There are 508 Stars in the Sky by Marky Allen.  Two girls sit in the backyard and count the stars.

Sky is Full of Stars by Franklyn Branley.  Good information on the sky and its stars.

The Sun: Our Very Own Star by Jeanne Bendick.  A basic book on the star we call our sun.

Follow the Drinking Gourd by Jeanette Winter.  A wonderful book about slaves following the big dipper to freedom.