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Lesson plan Grade 4 Science

Placing Bellwood's New Water Tower: A Topographic Map Lesson

A grade 4 lesson where students read an elevation table standing in for a topographic map of the fictional town of Bellwood and find elevation differences.

Objectives

  1. Students will interpret a table of elevation points near Bellwood to identify areas of higher and lower land.
  2. Students will calculate the difference in elevation, in feet, between two points on the map.
  3. Students will explain why water utilities build towers on the highest available land near a town.

Vocabulary

Key words: topographic map, contour line, elevation, gravity

Teacher overview

The town of Bellwood needs a new water tower, and the town council has asked its fourth-grade class to help decide where it should stand. This lesson uses a simple elevation table, standing in for a topographic map, so students can practice reading elevation data before they ever see a full contour map in later grades. A common misconception this lesson addresses directly is that a water tower's tank simply "holds" water for later use; the real reason towers sit on the highest available land is that gravity pushes water downhill through pipes to homes at lower elevation, which is why elevation, not just distance, decides a good tower site.

Procedure

Hook (5 min): Tell students that Bellwood needs a new water tower and that engineers usually try to build towers on high land near town. Ask: "Why would builders want the highest spot, instead of the spot closest to the town center?" Collect a few guesses without confirming or correcting them yet.

Direct instruction (15 min): Introduce the term elevation, the height of a point of land above sea level, and explain that a topographic map uses contour lines to show elevation across an area. Display this table of six Bellwood landmarks and their elevations:

Landmark Elevation (feet)
North Ridge (proposed tower site) 660
Town Hall 620
Cedar School 615
Elm Park 610
Oak Street neighborhood 600
Mill Pond 590

Explain that once water sits in a tower on high ground, gravity alone can push it downhill through pipes to every lower point in town, keeping a steady flow at homes without the pump running constantly. Model one subtraction example on the board: North Ridge (660 ft) is how much higher than Mill Pond (590 ft)? 660 − 590 = 70 feet.

Guided practice (15 min): In pairs, students find two more elevation differences using the table: how much higher is North Ridge than Town Hall (660 − 620 = 40 ft), and how much higher is North Ridge than Cedar School (660 − 615 = 45 ft). Circulate and check that students are subtracting the lower elevation from the higher one, not the reverse.

Independent practice (10 min): Each student completes three handout problems using the same table: the difference between North Ridge and Oak Street, a comparison of which of two landmarks sits closer in elevation to North Ridge, and a "why" question connecting elevation to water pressure.

Closure / exit ticket (5 min): Students answer one question on an index card: "If the tower is built at North Ridge (660 ft) and a new house is built at 605 ft, how many feet will the water 'fall' on its way to that house?" Collect the cards and scan for the correct subtraction method before dismissal.

Placing Bellwood's New Water Tower: A Topographic Map Lesson — Grade 4 Science
Name: ____________________________ Date: ______________

Student Handout

Bellwood is a fictional town, and every elevation below is measured in feet above sea level. Show your subtraction for each question.

  1. North Ridge, the proposed water tower site, stands at 660 feet. Town Hall stands at 620 feet. How many feet higher is North Ridge than Town Hall?
  2. North Ridge stands at 660 feet and Cedar School stands at 615 feet. How many feet higher is North Ridge than Cedar School?
  3. North Ridge stands at 660 feet and the Oak Street neighborhood stands at 600 feet. How many feet higher is North Ridge than Oak Street?
  4. Town Hall stands at 620 feet and Elm Park stands at 610 feet. Which of these two landmarks sits closer in elevation to North Ridge at 660 feet?
  5. Why do water utilities build their towers on the highest land they can find near a town?
  6. The tower is built at North Ridge, 660 feet, and a new house is built at 605 feet. How many feet will the water "fall" on its way to that house?

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: 40 ft.
    Guided practice, North Ridge vs. Town Hall: 660 ft − 620 ft = 40 ft.

  2. Answer: 45 ft.
    Guided practice, North Ridge vs. Cedar School: 660 ft − 615 ft = 45 ft.

  3. Answer: 60 ft.
    Independent practice, North Ridge vs. Oak Street: 660 ft − 600 ft = 60 ft.

  4. Answer: Town Hall.
    Independent practice, closer landmark. Town Hall is 660 − 620 = 40 ft below North Ridge, while Elm Park is 660 − 610 = 50 ft below North Ridge. Because 40 ft is a smaller difference than 50 ft, Town Hall sits closer in elevation to the proposed tower site.

  5. Answer: Gravity pulls water downhill.
    Independent practice, why elevation matters. A tower built on high ground lets gravity push water through the pipes to lower points in town without the pump needing to run all the time.

  6. Answer: 55 ft.
    Exit ticket: 660 ft − 605 ft = 55 ft of elevation for the water to fall on its way to the new house.

Differentiation

Support (below grade level)

Provide the subtraction problems as a fill-in vertical subtraction frame (with the larger number already placed on top) so students focus on the borrowing steps rather than deciding which number goes first. Reduce the independent practice to two problems instead of three.

Extension (above grade level)

Ask students to rank all six landmarks from highest to lowest elevation and then calculate the elevation difference between every pair of neighboring landmarks in that ranked list, checking that the differences add up correctly across the full range from Mill Pond to North Ridge.

ELL supports

Pre-teach elevation, contour line, and gravity using a simple side-view sketch of a hill with the tower on top and houses at different heights along the slope, labeled in English and, where possible, in students' home languages. Allow the exit ticket to be answered with a drawn diagram plus the subtraction, rather than a full sentence.