This proposal is to develop an environmental engineering laboratory based on collaborative and active learning to provide undergraduate engineering students practical, hands on experience with topics and concepts typically not covered in undergraduate environmental laboratories. The laboratory will also be used for demonstrations to high school and first year engineering students so that they will be able to experience the practical side of engineering. Most environmental engineering laboratory exercises follow a simple one-two-three approach which neither stimulates critical thinking nor enhances learning. Practical aspects of topics which students are likely to encounter on the job are, at best, discussed only in the classroom and graduates reach the job market with limited practical experience. The proposed laboratory will engage groups of students in problem solving using four common conventional technologies in environmental engineering but seldom experienced during undergraduate education: Mixed tank reactors, Trickling filters, Growth kinetics of microbial decomposition, and Disinfection. Laboratory assignments will concentrate on one of the specific technologies. Students will work in small groups (3-4/grp) and will be presented with typical engineering tasks and/or problems, e.g., students may be asked to determine the optimum design of a trickling filter system, the extent of mixing in a mixed tank reactor, or how a certain variable, such as pH, affects microbial growth. Students will research the topic, discuss the problem in groups, and develop a procedure which will yield the desired solution. Students will develop a workplan intended to solve the problem, followed by a written formal laboratory report stating conclusions and detailed discussion of the final proposal, alternatives considered and possible modifications. As a result of this process, it is expected that students will be better prepared for the work place they are likely to encounter.