I live in arid Southern California where surface water is scarce and it is impossible for my students to measure Biological Oxygen Demand in person. So, I filmed the process for my students. Students filled in part of their Water Quality Virtual Lab using these videos.
After watching this video and calculating water quality for three samples based on BOD, students watched this video explaining it.
My students drew the curve to match my drawing (starting at about 2 minutes.
This year, I also did Fecal Coliform Bacteria to save funds for other materials.