Lesson plan Grade 7 Engineering & Design
Sablewood Creek Monitoring Plan: Designing to Detect Pollution
Students design a water-quality monitoring plan for a fictional creek, choosing sampling sites and tests to detect three pollution sources within real limits.
Objectives
- Students will design a water-quality monitoring plan that names sampling locations, tests, and a sampling schedule.
- Students will justify their sampling choices against stated criteria and constraints for the monitoring project.
Vocabulary
Key words: monitoring, sampling site, upstream, downstream, criteria, constraint
Teacher overview
In this lesson students act as engineers hired to design a water-quality monitoring plan for Sablewood Creek, a fictional stream that runs past three possible pollution sources: a farm, a road crossing, and a new housing development. A monitoring plan is the part of the design that tells a community whether the water is changing and where a problem is coming from. Students decide where to sample, what to measure, and how often, then defend those choices against real limits on time, kits, and money. The lesson centers on a design idea students often overlook: a good monitoring plan needs a clean upstream reading to compare against, or there is no way to tell whether a source is actually adding pollution.
Procedure
Hook (5 min): Draw or project a simple sketch of Sablewood Creek based on the handout description and ask: "If you could only test the water in three spots to find out who is polluting this creek, where would you test, and why?" Take a few answers without judging them. Tell students that professionals make this exact decision, and that today they will design the plan.
Background (10 min): Introduce the three sources along the creek: a farm that may add nutrients from fertilizer, a road crossing that may add oil and grit, and a housing development that may add sediment during construction. Introduce four common tests a field team can run: turbidity (cloudiness), dissolved oxygen, nitrogen and phosphorus (nutrients), and temperature. Note two benchmarks students may use: most fish need dissolved oxygen above 5 mg/L, and healthy creeks usually stay cool and clear.
Model the design move (10 min): On the board, place one sampling site upstream of all three sources and explain why: it gives a "before" reading to compare every downstream site against. Add a site just below the farm and ask what test would reveal a fertilizer problem there (nutrients). Emphasize that each site should be chosen to answer a specific question, not placed at random.
Group design work (20 min): In groups of three or four, students complete the Student Handout. They mark four to six sampling sites on the map, choose which tests to run at each, set how often to sample, and write the plan's criteria and constraints. Circulate and push each group to justify at least one site choice out loud.
Share (5 min): Two groups post their maps and explain one site choice and one constraint they had to work around. The class compares whether both plans included an upstream reference site.
Closure and exit ticket (5 min): Each student answers one question on an index card: "Why does a monitoring plan need at least one sampling site upstream of every pollution source?" Collect the cards; the class has met the lesson goal if at least 80 percent of students name the need for a clean comparison reading.
Student Handout
You are designing a monitoring plan for the fictional Sablewood Creek. Along the creek are three possible pollution sources: a farm, a road crossing, and a housing development. Your field team has four tests available: turbidity, dissolved oxygen, nutrients (nitrogen and phosphorus), and temperature.
On your map, Sablewood Creek flows from north (top) to south (bottom). Going downstream, it passes the farm on the west bank, then the road crossing, then the housing development on the east bank, before it reaches the town.
Mark four to six sampling sites on your creek map. Include at least one site upstream of all three sources. Label each site with a number.
For each site, list which of the four tests you would run there, and write one sentence saying what that site is meant to find out.
Write a sampling schedule: how often will your team collect samples (for example, weekly, monthly, or after every heavy rain), and why did you choose that timing?
Write two criteria your plan must meet (what a successful plan must do) and two constraints your plan must work within (limits you cannot change).
Your team only has enough kits to run 10 tests per visit. Explain one choice you made to stay within that limit while still watching all three sources.
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Answer Key
Answer: Accept any map with four to six numbered sites that includes at least one clearly upstream of the farm, the road, and the development. The upstream site is required; it provides the clean baseline every downstream reading is compared against.
Answer: Accept reasonable test-to-site matches: nutrients below the farm, turbidity below the construction site and the road, dissolved oxygen and temperature at downstream sites. Each site's stated purpose should match the test chosen.
Answer: Accept weekly, monthly, or event-based schedules that are justified. Strong answers add sampling after heavy rain, because rain washes pollutants off fields, roads, and bare construction soil all at once.
Answer: Accept two workable criteria (for example, "detect which source adds pollution" and "give results the town can act on quickly") and two real constraints (for example, "only 10 tests per visit," "limited budget," or "team can visit once a week").
Answer: Accept any choice that trims tests without losing coverage, such as running only the most relevant test at each site, or testing every site during dry weeks but adding extra nutrient tests below the farm after storms.
Differentiation
Support
Give these students a partly completed map with the upstream reference site already marked and one test already assigned, so they can focus on placing the remaining sites and matching tests. Provide a short list of which pollutant each source is most likely to add.
Extension
Have students add a cost to each test (a simple made-up price list) and redesign their plan to fit a fixed budget, then explain which readings they would give up first and why that trade-off is acceptable.
ELL supports
Provide a picture glossary for "upstream," "downstream," "sampling site," and each of the four tests, with a small icon beside each term. Allow students to label the map and answer items 1 and 2 with short phrases rather than full sentences.