CK-12 Foundation
Ck 12: Biology: Autotrophs and Heterotrophs
[Free Registration/Login may be required to access all resource tools.] Discusses how autotrophs and heterotrophs obtain energy.
CK-12 Foundation
Ck 12: Plix: Autotrophs and Heterotrophs
[Free Registration/Login Required] An interactive exercise regarding autotrophs and heterotrophs. You will need a sign-in to access this media, but it is worth your while!