There are many sources one could choose to find information on the life of the Buddha.  I will offer some web sites (see below Links and Texts), texts and videos.
A general outline you will find about the Buddha will be the following:  birth, life in the palace, the four sights, renunciation and enlightenment.

You may also wish to introduce your students to the Jataka tales.  It is said that the historical Buddha was a great storyteller and would frequently tell stories to get his message across.  There were stories told about the Buddha by his followers to explain and understand the Dharma.  The Jataka stories is a collection of hundreds of tales about the Buddha’s past lives.  In many of the stories you will find the Buddha appearing as an animal in order to teach the value of certain qualities one should possess.  There are many versions of these Jataka tales around.  Many are written for children in the form of comics.  I am offering one source that you may find appropriate for your students, but do not neglect to find the comic versions as well.
Stories of the Buddha, Being Selections from the Jataka.  Translated and Edited by Caroline A. F. Rhys Davids, Dover Publications, Inc., NY, NY

Video:

Little Buddha
In many ways Little Buddha is a companion piece to Bernardo Bertolucci's The Last Emperor. A beautiful travelogue and history lesson unfolds in the two parts of this film: a historical text of Siddhartha (Keanu Reeves) and the contemporary quest of Lama Norbu (Ying Ruocheng), who believes he has found the reincarnation of his former teacher in a Seattle child. The ancient, magical tales sweep away the blasé contemporary action. Ruocheng's presence drives the story of discovery as the child learns about the teachings of Buddhism. A visual feast that will dazzle both young and old. In fact, were it not a religious icon, the youngsters might want Siddhartha dolls after viewing his magical on-screen adventures. Beautiful cinematography by Vittorio Storaro. --Doug Thomas --This text refers to the VHS Tape edition  - From http://www.amazon.com

Comment:  I show this video more for the story of the Life of the Buddha.  I personally feel there is just too much going on in this video, but it gives a good visual.  My students enjoy this video very much.

Schlessinger Media also has a World Religions video series.  I have used them all.  I have to admit that while they are an excellent resource for the teacher, the students have a more difficult time with it.  I would not use it with students under 12th grade.  Information on the series may be found at: http://www.libraryvideo.com
Here is the blurb from the company:
Narrated by Academy Award winner Ben Kingsley, Religions of the World is a 13-part series that offers insights into the striking similarities and vast differences among the world's major religions as well as the unique perspective of its many individual cultures. Each episode presents a fresh look at the history of our world through the eyes of religion as well as an in-depth look at religion's role in creating cultural diversity. Each program includes a Teacher's Guide.