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Classroom activity Grade 6 Engineering & Design

Corrantry Hill Pressure Zone Placement Activity

Groups act as a utility design team, finding water pressure at six houses on a fictional hillside and deciding which ones belong in a booster-served upper zone.

Objectives

  1. Students will multiply an elevation difference by a decimal constant to find water pressure at a house.
  2. Students will sort houses into two pressure zones using stated minimum and maximum pressure limits.
  3. Students will explain why a booster pump station is needed at a particular place on a slope.

Vocabulary

Pressure zone
A pressure zone is a section of a water system that a utility manages separately because it sits at a different elevation than the rest of the town. Utilities create pressure zones so that water pressure stays safe and steady for everyone, whether they live at the bottom of a hill or near the top.

Also: elevation, booster pump station, head

Teacher overview

Corrantry Hill is a fictional neighborhood on a long slope below a water storage tank at the top of the hill, and every elevation and price used here was invented for the activity. Groups of three act as a utility design team. Each group receives six house cards showing an address and a ground elevation, and the group calculates the water pressure at each house from the height of water above it, using the rule that one foot of elevation difference produces 0.433 psi. Sorting the six cards into a lower zone and a booster-served upper zone is the same decision a utility makes when its service area climbs a hill, because the houses that fall below the minimum pressure are the customers a booster pump station has to serve.

Activity Directions

All elevations, pressures, and limits used in this fictional Corrantry Hill scenario are invented for teaching.

  • Setup (5 min): Form groups of three and give each group one set of six house cards, one handout per student, and one calculator per group. Tape a long strip of paper to the board and mark the tank's water surface at the top so the class shares one picture of the hill. Assign roles: one student reads elevations aloud, one records, one checks the arithmetic.
  • Round 1, calculate the pressures (12 min): Groups work handout items 1 through 7, finding the elevation difference for each house and multiplying it by 0.433. Require the recorder to write each pressure on the matching house card in pencil, so the cards become the group's data.
  • Round 2, sort the zone (10 min): Groups lay the six cards in elevation order on the desk and draw a physical line with a ruler between the houses that meet the minimum pressure and the houses that do not, then answer handout item 8. Tell groups the line they draw is the pressure zone boundary and that the booster station will sit just below it.
  • Round 3, check the boost (8 min): Groups answer handout items 9 and 10, which test whether adding the booster pushes any house above the utility's upper pressure limit. A group that finds a house over the limit must say what it would do about that house.
  • Presentations (6 min): Each group states, in one sentence, which houses it put in the upper zone and what pressure the highest house would have after the boost. Record the boundaries on the board so the class can see whether every group drew the same line.
  • Debrief (4 min): The activity ends after the presentations. Ask two questions. First, why does a house higher on the hill have lower water pressure even though it is closer to the tank on a map? Second, why does the utility care about a maximum pressure as well as a minimum?
Corrantry Hill Pressure Zone Placement Activity — Grade 6 Engineering & Design
Name: ____________________________ Date: ______________

Student Handout

Corrantry Hill and every number below are fictional, invented for this activity. The water tank's surface sits at an elevation of 520 feet. One foot of elevation difference equals 0.433 psi. Round every pressure to the nearest tenth.

House Ground elevation
House 1 380 feet
House 2 405 feet
House 3 430 feet
House 4 455 feet
House 5 470 feet
House 6 495 feet
  1. House 1 sits at 380 feet and the tank surface is at 520 feet. What is the difference in feet?
  2. Multiply your answer to item 1 by 0.433. What pressure does House 1 have?
  3. What pressure does House 2 have?
  4. What pressure does House 3 have?
  5. What pressure does House 4 have?
  6. What pressure does House 5 have?
  7. What pressure does House 6 have?
  8. The utility requires at least 40 psi at every house. Which houses fall below that?
  9. A booster pump station would add 35 psi to every house in the upper zone. What pressure would House 6 have after the boost?
  10. The utility also keeps pressure at or below 80 psi. After the boost, House 3 would read 74.0 psi. Does House 3 stay within that limit?

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: 140 feet. The tank surface is at 520 feet and House 1 sits at 380 feet, so 520 - 380 = 140 feet.
  2. Answer: 60.6 psi. 140 x 0.433 = 60.62, which rounds to 60.6 psi.
  3. Answer: 49.8 psi. The difference is 520 - 405 = 115 feet, and 115 x 0.433 = 49.795, which rounds to 49.8 psi.
  4. Answer: 39.0 psi. The difference is 520 - 430 = 90 feet, and 90 x 0.433 = 38.97, which rounds to 39.0 psi.
  5. Answer: 28.1 psi. The difference is 520 - 455 = 65 feet, and 65 x 0.433 = 28.145, which rounds to 28.1 psi.
  6. Answer: 21.7 psi. The difference is 520 - 470 = 50 feet, and 50 x 0.433 = 21.65, which rounds to 21.7 psi.
  7. Answer: 10.8 psi. The difference is 520 - 495 = 25 feet, and 25 x 0.433 = 10.825, which rounds to 10.8 psi.
  8. Answer: Houses 3, 4, 5, and 6. Their pressures of 39.0, 28.1, 21.7, and 10.8 psi are all below the 40 psi minimum, while Houses 1 and 2 are above it.
  9. Answer: 45.8 psi. House 6 reads 10.8 psi, and 10.8 + 35 = 45.8 psi after the boost.
  10. Answer: Yes. House 3 would read 74.0 psi, which is below the 80 psi upper limit, so no pressure reducing valve is needed there.

Differentiation

Support

Give these students house cards on which the elevation difference is already printed beside the elevation, so the multiplication in items 2 through 7 can begin without a subtraction step. Provide one fully worked card as a model taped to the desk.

Extension

Ask groups to place a seventh house at an elevation they choose in this fictional neighborhood, calculate its pressure, and state whether the booster would put it above the utility's upper limit, then propose where they would draw the zone line if the tank surface were 20 feet lower.

ELL supports

Provide a side-view drawing of the hill with the tank at the top, the six houses drawn along the slope, and the words "elevation," "difference," and "pressure" labeled with arrows. Allow students to record items 2 through 7 in a prepared chart and to answer item 8 by circling house numbers.

Extensions

Have students find the elevation of their own school and of a point about a mile away using a public topographic map, then calculate the pressure difference those two elevations would produce if both were fed from the same tank, keeping the calculation clearly separate from the fictional Corrantry Hill figures.