This document contains hands-on, open-ended laboratory activities that can be done in the classroom on a shoestring budget. They are aimed at increasing students' excitement and curiosity about science and enabling them to develop a better understanding of the nature of science, take an active role in their own learning process, and develop critical thinking skills. Each lab contains directions for teachers that include objectives, synopsis, level, connections, getting ready, teacher background, teaching tips, safety procedures, instructional procedures, student design of the next experiment, suggested modifications for students who are exceptional, test questions and answers, references, and suggested readings. Directions for students include introduction, safety notes, hypothesis generation, plan of investigation, questions/analysis and/or lab report format, and design for the next experiment. These labs are based on research about constructivism and conceptual change and emphasize cooperative learning. Topics include designer planes, acid rain, enzymes, biological levers, ethology, taste and smell, muscular activity, growth patterns and genetics, invertebrates, insecticidal effects of plant compounds, over-the-counter drugs, ecology, leaf litter, proteins, roots, and plant growth. Appendices include bottle biology experiments, care of mealworms, field trips, and supplementary materials. (JRH)