The research focus of this proposal is the impact of innovative and widely advocated methods of teaching introductory biology on a broad sample of UMBC undergraduates. A 2X2 longitudinal study is proposed to examine whether early exposure to student-centered, active-learning classes and investigative laboratories in introductory biology makes a difference over multiple years with respect to students' achievement, attrition, and attitudes and beliefs toward and about the nature of science. Students who register for class and laboratory sections (class and lab are separate courses) experience one of four pairings of lecture and lab (for example, traditional lecture/investigative lab, active-learning lecture/tradtional lab, etc.). The question is whether long-term outcomes differ significantly depending on which class/laboratory combination students experience.