When African American students write or say "Mama jeep is out of gas" or "The Earth revolve around the sun," many teachers--labeling this usage poor English or bad grammar--assume that their students have problems with possession or don't know how to make subjects and verbs agree. Forty years of linguistic research, however, demonstrates that the student is not making errors in Standard English--the child is writing or speaking correctly in the language patterns of the home and of the community. Building on the linguistic knowledge that children bring to school becomes the focus of this book, which advocates the use of "code-switching" to enable students to add another linguistic code--Standard English--to their linguistic toolbox.