Crustal Evolution Education Project (CEEP) modules were designed to: (1) provide students with the methods and results of continuing investigations into the composition, history, and processes of the earth's crust and the application of this knowledge to man's activities and (2) to be used by teachers with little or no previous background in the modern theories of sea-floor spreading, continental drift, and plate tectonics. Each module consists of two booklets: a teacher's guide and student investigation. The teacher's guide contains all of the information present in the student investigation booklet as well as: (1) a general introduction; (2) prerequisite student background; (3) objectives; (4) list of required materials; (5) background information; (6) suggested approach; (7) procedure, recommending one 45-minute class period for this module; (8) summary questions (with answers); (9) extension activities; and (10) list of references. Focusing on a land bridge (connection between two land masses), students explain how the Bering Land Bridge first became possible, list two animals that migrated during each of the two major time periods, and explain two ways for a land bridge to become exposed or submerged. (Author/JN)