This project is designed to strengthen the teaching of biology at the college. Students in upper-division courses often tend to compartmentalize the concepts and laboratory skills learned in one course and do not carry them over to the problems encountered in other courses. This project develops a series of experiments that involve the laboratory students of two different courses within the same semester. In addressing a routine problem, students in Course 1 identify an aspect of the problem that is beyond the scope of their course. They engage the students in Course 2, who bring the techniques and expertise of their course to the problem-solving process. The students in the two courses work collaboratively to address the problem, each using their specialized knowledge base, problem-solving skills and experimental approaches. The project targets students enrolled in one 200-level course (Microbiology) or one of four 300- or 400-level courses (Cell Biology, Genetics, Biochemistry and Developmental Biology). Assistance was received in the C. elegans experiments from Andrew Fire, Ph.D., at the Carnegie Institute in Baltimore, Maryland. This series of laboratory sequences affects the biology students in several ways. Students are challenged to integrate concepts and skills across the various disciplines of the biological sciences. They use the same experimental organisms in the laboratory component of several courses and come to an understanding of the general applicability of these model systems in biological research. They use many of the same techniques of cell and molecular biology to address a variety of problems. They are required to communicate their experimental findings clearly to their collaborators in the cross-over lab, thus strengthening their writing and oral communication skills. This approach to teaching can be adopted by other institutions that are interested in the development of their students as active biologists.