Thirst for a Solution: Alginate Biopolymer Experiments for the Middle and High School Classroom

Comprehensive curricula are described for middle and high school classrooms built around the synthesis of biodegradable calcium alginate capsules prepared from food-safe chemicals. Experiments and activities question whether calcium alginate capsules are a viable alternative to single-use water bottles and consider what characteristics are required to become commercially successful. Students prepare calcium alginate capsules using sodium alginate and calcium lactate and observe the physical properties of the fluid-filled pod. In the high school curriculum, capsules using alternative group 2 cation salts are made and compared qualitatively to the calcium alginate capsules. After exploring the capsules, students work collaboratively to design an inquiry experiment. The high school curriculum offers extensions such as analyzing a related literature article and creating professional research posters on their inquiry experiments. The middle school curriculum includes a scaffolded introduction on the topics of renewable vs nonrenewable resources and introduces simple polymer definitions and the concept of cross-linking through use of models. Both curricula align with Next Generation Science Standards (NGSS) around designing solutions to modern problems and carrying out investigations. Additionally, the experiment is ideal for safe, remote-learning instruction. Overarching connections between science and society are highlighted through the global plastics problem, and potential solutions are presented using the green chemistry principles of renewable feedstocks, design for degradation, and less hazardous chemical synthesis.