Student teams design and then create small-size models of working filter systems to simulate multi-stage wastewater treatment plants. Drawing from assorted provided materials (gravel, pebbles, sand, activated charcoal, algae, coffee filters, cloth) and staying within a (hypothetical) budget, teams create filter systems within 2-liter plastic bottles to clean the teacher-made simulated wastewater (soap, oil, sand, fertilizer, coffee grounds, beads). They aim to remove the water contaminants while reclaiming the waste material as valuable resources. They design and build the filtering systems, redesigning for improvement, and then measuring and comparing results (across teams): reclaimed quantities, water quality tests, costs, experiences and best practices. They conduct common water quality tests (such as turbidity, pH, etc., as determined by the teacher) to check the water quality before and after treatment.

After watching a short online video that recaps the enormous scale of accumulating plastic waste in our oceans, student teams are challenged to devise a method to remove the most plastic microbeads from a provided commercial personal care product—such as a facial cleanser or body wash. They brainstorm filtering methods ideas and design their own specific procedures that use teacher-provided supplies (coffee filters, funnels, plastic syringes, vinyl tubing, water, plastic bags) to extract the microplastics as efficiently as possible. The research and development student teams compare the final masses of their extracted microbeads to see which filter solutions worked best. Students suggest possible future improvements to their filter designs. A student worksheet is provided.

Students are introduced to the growing worldwide environmental problems that stem from plastic waste. What they learn about microplastics and the typical components of the U.S. water treatment process prepares them to conduct three engaging associated activities. During the lesson, students become more aware of the pervasiveness and value of plastic as well as the downstream pollution and health dangers. They learn how plastic materials don’t go away, but become microplastic pollution that accumulates in water resources as well as human and other animal bodies. They examine their own plastic use, focusing on what they discard daily, and think about better ways to produce or package those items to eliminate or reduce their likelihood of ending up as microplastic pollution. A concluding writing assignment reveals their depth of comprehension. The lesson is enhanced by arranging for a local water treatment plant representative to visit the class for Qs and As. In three associated activities, students design/test microplastic particle filtering methods for commercial products, create mini wastewater treatment plant working models that remove waste and reclaim resources from simulated wastewater, and design experiments to identify the impact of microplastics on micro-invertebrates.

Student teams investigate the migration of small-particle plastic pollution by exposing invertebrates found in water samples from a local lake or river to fluorescent bead fragments in a controlled environment of their own designs. Students begin by reviewing the composition of food webs and considering the ethics of studies on live organisms. In their model microcosms, they set up a food web so as to trace the microbead migration from one invertebrate species to another. Students use blacklights and microscopes to observe and quantify their experimental results. They develop diagrams that explain their investigations—modeling the ecological impacts of microplastics.