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Lesson plan Grade 5 Math

Sandlily Reservoir's Water Level: A Grade 5 Graphing Lesson

A grade 5 lesson where students plot a fictional reservoir's weekly water level as ordered pairs on a coordinate grid and interpret the drought trend they graph.

Objectives

  1. Students will plot ordered pairs on a coordinate grid to represent a reservoir's water level over time.
  2. Students will read specific coordinate points to answer questions about the reservoir's condition in a given week.
  3. Students will calculate the change in water level between two given points on the graph.

Vocabulary

Reservoir
A human-made lake, usually created by a dam, that stores water for later. Reservoirs supply cities and farms and help control floods.
Drought
A long stretch of drier-than-normal weather that leaves too little water for people, farms, and nature. Droughts build slowly and can last for years.

Also: coordinate grid, ordered pair, x-axis, y-axis

Teacher overview

Sandlily Reservoir, a fictional reservoir used for this lesson, supplies a nearby town's drinking water and has been dropping steadily through a dry summer. Water managers watch a reservoir's level over time the same way this lesson asks students to: as a set of points on a graph, with the week number along one axis and the water depth in feet along the other. A common misconception in this lesson is that students read only the y-value of a point and ignore the x-value, so an exercise built into guided practice asks students to state both coordinates together every time they name a point, not just the water depth.

Procedure

Hook (5 min): Describe (or show a photograph of) a reservoir with a visible "bathtub ring" of lighter-colored rock above the current waterline. Ask students what could explain a ring like that, and record their ideas on the board.

Direct instruction (10 min): Introduce a coordinate grid where the x-axis represents the week number (0 through 8) and the y-axis represents the reservoir's water depth in feet (0 through 90). Model plotting the first two points as a class: (0, 80) and (2, 74). Explain that each ordered pair tells both which week it is and how deep the water was that week.

Guided practice (15 min): In pairs, students plot three more points: (4, 66), (6, 55), and (8, 40). As they plot each point, partners say both coordinates aloud, for example "week 4, 66 feet." They connect the five points in order with a ruler and describe, in one sentence per pair, what the line's downward direction shows about the reservoir.

Independent practice (10 min): Each student answers two numbered questions on the handout:

  1. What was the reservoir's water level, in feet, during week 4?
  2. Find how many feet the water level dropped in each two-week interval (week 0 to 2, week 2 to 4, week 4 to 6, and week 6 to 8), then name the interval with the largest drop.

Closure / exit ticket (5 min): Students answer one question on an index card: "If the reservoir kept dropping about 15 feet every two weeks, what water level would you predict for week 10?" Collect and scan for reasoning that starts from the week 8 value before dismissal.

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: 66 ft.
    Reading directly from the plotted point (4, 66), the water level during week 4 was 66 feet.
  2. Answer: weeks 6-8.
    Week 0 to 2: 80 - 74 = 6 ft. Week 2 to 4: 74 - 66 = 8 ft. Week 4 to 6: 66 - 55 = 11 ft. Week 6 to 8: 55 - 40 = 15 ft. The largest drop, 15 feet, happened between weeks 6 and 8.
  3. Exit ticket answer: 25 ft.
    Using the week 6-8 drop of 15 feet as the pattern, week 8's level of 40 feet minus 15 feet gives a predicted week 10 level of 25 feet.

Differentiation

Support (below grade level)

Provide a printed coordinate grid with the axes already labeled and the first two points already plotted, and give students a printed data table listing each week's number and water depth so they only need to locate and mark points, not record the data themselves.

Extension (above grade level)

Ask students to calculate the average drop per two-week interval across the full 8 weeks (80 feet minus 40 feet, divided by 4 intervals) and compare that average to the largest two-week drop they found in independent practice, explaining why the two numbers differ.

ELL supports

Pre-teach "ordered pair," "axis," and "coordinate" using a simple two-column chart (week number, water depth) alongside the grid, with the words labeled in English and, where possible, students' home languages. Provide a sentence frame: "In week ___, the water level was ___ feet."

Extensions

Have students research a real local reservoir, lake, or pond's typical seasonal level pattern from a parent, librarian, or local water utility, then sketch a rough coordinate graph of what they learn and compare its shape to Sandlily's drought graph.