The Underground Railroad is sometimes hard for students to understand. Here are some good resources for you to use in your classrooms.
National Geographic The Underground Railroad - Using the drop down menu you can get several pages of information to use with your class. There is a time line, a game called The Journey, for Kids, and Faces of Freedom.
Interactive Map - This is a nice interactive map that shows the routes out of the slave states to Canada, Mexico, and the Caribbean.
Underground Railroad Flight to Freedom Program - This is a neat page with several interactive activities. Make sure you check out the activity at the top of the page.
Scholastic The Underground Railroad - This was made for an interactive white board but could be used in other ways as well. The page also has teacher resources, slide shows, activities, and printables (one is a min-book).
Songs of Freedom - This page gives the background on some of the songs sung by the slaves including Follow the Drinking Gourd, Swing Low Sweet Chariot, and Wade in the Water.