Book excerpt: Chip and Marty fall asleep in Mr. Sandman's U.S. history class again! This time they wake up in the 1850's as slaves. Learn what life was like 250 years ago as the boys have to work hard picking cotton on a southern plantation. Their only hope for escape is through the secret system known as the underground railroad. With the help of people like Harriet Tubman and a kind landowner named Mr. Freeman, the boys just might make it to New York ...and freedom. Join Chip and Marty on this fun-filled, fact-packed adventure on the underground railroad! Other books by Amy Fisher: The Adventures of Chip and Marty in Mr. Sandman's Class Cahokia—A U.S. Historical Fiction Novel