This is an activity (located on page 3 of the PDF under Water Clean-up Activity) about the use of reduction agents to decontaminate ground water. Learners will conduct a reduction-oxidation (redox) reaction in which vitamin C acts as a reduction agent after passing through a model of top soil, sand, and gravel to "pollutants" (starch-iodine mixture). This simulates how nanoparticles of iron are being used to detoxify water under former factory sites. Relates to linked video, DragonflyTV Nano: Water Clean-up.