Lesson Plan

How Clear Is the Water?

front end of a kayak in a blue lake, looking out toward cloud-covered mountains
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Grade Level:
Seventh Grade-Twelfth Grade
Biology: Animals, Biology: Plants, Chemistry, Climate Change, Ecological Engineering, Ecology, Environment, Physical Science
6-8 Class periods (50 minutes each)
Group Size:
Up to 36 (6-12 breakout groups)
National/State Standards:
HS-LS2 Ecosystems: Interactions, Energy, and Dynamics
HS-ESS2 Earths Systems
HS-ETS1 Engineering Design
ecosystem, turbidity, water quality, secchi disk


In this lesson students will test their knowledge of ecosystems and the qualities necessary to sustain life by creating Secchi disks, testing turbidity (water clarity), and making predictions about the habitat that might exist. This fun, hands-on lesson allows students to be the scientist and make predictions based on their findings in their lab reports.


  • Students will be able to explain the impact of water clarity on ecosystems functionality.
  • Students will create a product to analyze a solution.
  • Students will complete a lab report.


Many marine or aquatic ecosystems depend on the quality or productivity of water. Water heavy with glacial sediment is often not highly productive because of the silt concentration and temperature, where salt water tends to be warmer and teeming with life. Students will be working in a local lake or ocean (or classroom if you don’t have a nearby body of water) to test its turbidity and analyze the life that resides in the body of water.

The final result should be a lab report and an engineered product that students have taken time to create and explain. This lesson fits well with an engineering project or into an ecology lesson. The goals are to engage students in the water near them,with the life around them and to have them think of creative solutions to sustain their environment.


The materials with the PDF lesson are all inclusive. It is a presentation to start students off and spearhead the lesson. There is an activity manual with all the portions suggested in the procedure as a template for teachers to use and hand out.


Part 1: Introduce the topic to students as either a part of a stand-alone lesson or as a part of a climate change, ecology, or engineering lesson. Starting with the introductory presentation, talk students through the ideas of water quality and its importance to the ecological world. Take time to chat and have students respond to the “Let’s Consider” sections found in the presentation. (50 min)

Part 2: In the activity manual, start with the Turbidity Lab. Divide students into groups, have them review the information from the presentation and answer the preliminary questions – remember that for this lab, you will need to be near a body of water. If you are not near water, please look at the end of the lesson for ways to make it a classroom activity. Students should work through the lab with their partners (this will take different amounts of time for different students); a suggested time is 2-3 class periods (50 min each)

Part 3: Once you have finished the lab, you can take it a step further and work through the engineering assessment. Students should be given a range of materials or bring their own materials in to create a Secchi disk.

The goal behind the engineering portion is for students to realize a problem related to the turbidity of water, brainstorm a creative solution, and test a product they have created. There is a template to take students through the engineering process in the activity manual. With this activity, you can suggest students look at the ecology of an area, the plants and animals who live within a body of water, a better Secchi disk design that makes it easier to record, or a Secchi disk that tests for something other than turbidity (dissolved oxygen, pH, etc.). The idea is that students are using their brains to create something new. (2-3 50 min periods)

Part 4: The final assessment should be a complete lab write up. In the activity manual there is an outline of a lab write up, but you can modify it depending on your requirements. The lab write up should be a comprehensive review of the engineering portion (what they created), with a solid foundation from the Turbidity Lab. Students can complete this activity as a group or as individuals. (1-2 50 min periods)


Students will create a lab report (to your specifications or the ones outlined in the lesson) for grading. Students will have a creatively engineered Secchi disk with explanation as to how it will work better and what its primary goal for data would be.

Park Connections

Lake Clark National Park and Preserve uses their Southwest Alaska Network (SWAN) team to measure, among other things, turbidity, dissolved oxygen content, pH, and temperature. They have been gathering data to analyze, as the climate is changing, glaciers are melting, and populations of salmon are fluctuating. The park is keeping a close eye on the water in Lake Clark and it’s surrounding lakes in an attempt to understand the importance of changes.


Teachers with an interested group of students can encourage their students to field test their created Secchi disks, perfect their disks, and retest them. Students can also create a report on a career as a scientist working on water quality monitoring, as a hydrological technician, or other related field.

Additional Resources

Students who are interested should check out the SWAN website. That can give them more information about the SWAN team, the projects that are ongoing, and a broader information base.


Secchi disk, water clarity (turbidity), ecosystem, productivity