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Classroom activity Grade 6 Science

The Bramwell Ridge Source Water Board: Forest or Filters

A 55-minute grade 6 activity in which teams score three source water plans for Bramwell against cost, habitat, storm reliability, and time to build.

Objectives

  1. Students will score three competing source water plans against four stated criteria.
  2. Students will name an ecosystem service a protected watershed provides that a treatment plant cannot.
  3. Students will defend a ranking of design solutions using evidence recorded on their scoring grid.

Vocabulary

Turbidity
Turbidity is a measure of how cloudy or murky water looks because of tiny particles floating in it. Clear water has low turbidity, and muddy water has high turbidity.

Also: source water, ecosystem service, criteria, trade-off

Teacher overview

This is a station-and-scoring activity for teams of four, running one full class period. Each team acts as the water board for the town of Bramwell and must choose among three plans for protecting the water it draws from Bramwell Creek: buy and protect the forested ridge that drains into the intake, build a filtration plant at the intake, or do a smaller version of both. The activity maps onto the concept directly, because each evidence card carries one criterion and teams cannot score a plan until they have read every card, which forces them to weigh purification, habitat, cost, and time against each other rather than choosing on first impression. The misconception worth naming beforehand is that a forest and a filter plant do the same job, when in fact only one of them also holds soil in place and shelters the creek that the plant depends on.

Activity Directions

  1. Setup before class (10 min of prep): Print one set of three option cards and one set of five evidence cards for each team of four, along with one scoring grid per student. Write the option cards from the three plan rows in the Student Handout, write four of the evidence cards from its cost, storm reliability, habitat, and build time entries, and write a fifth evidence card stating that a wildfire on the ridge would send far more soil into the creek during storms. Arrange desks into team clusters and place one set of cards face down at each cluster.

  2. Frame the problem (6 min): Tell students that the town of Bramwell draws its drinking water from Bramwell Creek, and that storms wash soil into the creek and make the water cloudy. Explain that cloudiness is measured in nephelometric turbidity units, written NTU, and that higher numbers mean dirtier water. Assign the four team roles: reader, recorder, timekeeper, and reporter.

  3. Read the options (6 min): The reader turns over the three option cards and reads them aloud. Option A is to buy and protect 4,000 acres of forest on Bramwell Ridge. Option B is to build a filtration plant at the creek intake. Option C is to protect 1,500 acres of the most important ridge land and build a smaller plant.

  4. Read the evidence (10 min): The reader turns over the five evidence cards one at a time, pausing after each so the recorder can enter the relevant facts on every student grid. The five cards cover cost, storm reliability, habitat, time to build, and wildfire risk. No scoring happens during this step.

  5. Score the plans (12 min): Each team scores all three options on all four criteria, using 1 for poor and 5 for excellent, and writes one sentence of justification beside each score. The timekeeper calls a two-minute warning. Teams that finish early add a fifth criterion of their own choosing and score it.

  6. Rank and post (8 min): Each team totals its scores, ranks the three options, and writes the ranking on chart paper with the two pieces of evidence that mattered most. Reporters post the chart paper on the wall.

  7. Gallery and vote (8 min): Teams walk the wall and read every posted ranking. Each student then casts one silent vote for the plan the town of Bramwell should adopt by placing a mark under one chart. The activity ends when every student has voted.

  8. Debrief (5 min): Ask two closing questions to the whole class. First, which single criterion changed the most rankings across the room. Second, what the forest does for the town of Bramwell that a filtration plant cannot do at any price. Then have students begin the handout questions, finishing any that remain as homework.

The Bramwell Ridge Source Water Board: Forest or Filters — Grade 6 Science
Name: ____________________________ Date: ______________

Student Handout

You are on the water board for the town of Bramwell. Your board must choose one plan for protecting the water the town draws from Bramwell Creek. All of the figures below come from the town engineer's report for this fictional project.

Plan Up-front cost Yearly cost Time to build Cloudy water it can handle Habitat protected
A: Protect 4,000 acres of ridge forest $9 million $200,000 2 years Storm turbidity stays near 4 NTU Nesting habitat for 12 bird species and a brook trout stream
B: Build a filtration plant $28 million $1.2 million 5 years Treats raw water up to 60 NTU None; the ridge could be logged or built on
C: Protect 1,500 acres and build a smaller plant $4 million plus $19 million $900,000 4 years Treats raw water up to 35 NTU The brook trout stream, but not all the nesting habitat

Score each plan from 1 to 5 on cost, storm reliability, habitat, and time to build. Then answer the questions.

  1. Which plan did your team rank first, and which single piece of evidence mattered most in that choice?
  2. Name one benefit the Bramwell Ridge forest provides for the town that the filtration plant cannot provide.
  3. Name one thing the filtration plant can do that the protected forest cannot do.
  4. Your team scored every plan on four criteria. Which criterion was hardest for your team to score, and why was it hard?
  5. Plan C costs more up front than Plan A and less than Plan B. Give one reason a town might choose Plan C anyway.
  6. Suppose a wildfire burned part of Bramwell Ridge next summer. Which plan would still deliver clean water to the town, and what evidence supports your answer?

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key
  1. Answer: Any of the three plans, paired with a specific evidence card.
    Accept any ranking that names one concrete piece of evidence, such as the up-front cost, the time to build, or the habitat protected. Do not accept a ranking justified only by preference.
  2. Answer: Habitat for the birds and the brook trout stream, or soil held in place on the slopes. Accept any answer naming a service the living forest provides beyond clean water, including habitat, erosion control, and shade that keeps the creek cool.
  3. Answer: It can treat very cloudy water, up to 60 NTU.
    Accept any answer noting that the plant works no matter what happens upstream, while the forest only helps if the land stays undisturbed.
  4. Answer: Any criterion, paired with a reason.
    Most teams name habitat or storm reliability as hardest, because those are not measured in dollars and require a judgment about what a service is worth. Accept any criterion when the reason describes a genuine difficulty in comparing unlike things.
  5. Answer: It gives some of both, so the town is not fully exposed if one part fails.
    Accept any answer naming a benefit of combining the two, such as keeping some habitat while still having treatment for the worst storms, or spending less than Plan B while getting more protection than Plan A.
  6. Answer: Plan B, and Plan C would also help.
    The evidence is the raw water each plan can treat. A burned slope sends far more soil into the creek, and only a plant can handle water that cloudy. Accept Plan C when students note that its smaller plant handles up to 35 NTU and may not be enough after a large fire.

Differentiation

Support

Give these students a scoring grid with the cost row already filled in and with the 1 to 5 scale labeled in words at each number. Pair them with a partner for the reading step so the five evidence cards are read aloud twice before any scoring begins.

Extension

Ask these students to propose a fourth plan for Bramwell, state its up-front cost, yearly cost, and build time, and score it on the same four criteria. They should then explain which existing plan their new one is most likely to beat and why.

ELL supports

Pre-teach "source water," "turbidity," and "trade-off" with a two-jar demonstration of clear and cloudy water beside a photograph of a forested hillside. Provide the option cards with a picture icon for each plan and sentence frames for the handout, such as "Our team chose Plan ___ because ___," and "The forest can ___, but the plant cannot ___."

Extensions

Have the class find out where your own community draws its drinking water and whether any of that land is protected, then write a short letter to the local water utility asking one question raised by the Bramwell activity. Reviewing the letters as a class before sending is a useful lesson in writing for a real audience.