I begin the lesson by asking students to describe what clean water looks, smells, and tastes like. Once we have a shared understanding of clean water, I ask students to discuss with their table groups how we could determine whether water is healthy or clean. To make this question more concrete, I display a vial of water and ask the class how they could determine whether the water was clean enough to drink, to use for bathing or washing clothes, or for watering their garden. I provide students with approximately five minutes of discussion time and monitor each student group during the discussion time.
I inform the class that there are a variety of scientific tests that they could use to determine whether my vial of water is clean enough for drinking or other uses. I provide each student with a copy of the background information handout which details each test of water quality. I inform the students that they will work with their table group to become experts on one water quality test. I provide each student group with a poster board which lists the title of one test. I ask that the students work together to read about their assigned test on the handout, to collaboratively decide which information is most important to share with the class, and to create a poster explaining their test to the class.
A sample of a completed student poster can be found here.
After each student group has completed their poster, I provide time for the student groups to share their work with their classmates. As the students present their findings, I require that the students in the audience take notes on the water quality test graphic organizer. This serves as a method to keep all students focused on learning and serves as a resource that students can refer back to during our subsequent work.
A video of one group presentation can be found here.