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Lesson plan Grade 6 Health & Consumer Science

The Okafor Family's Water Meter: A Grade 6 Home-Use Lesson

A grade 6 consumer-science lesson where students read a fictional family's water meter, find gallons used per person each day, and set a percent savings goal.

Objectives

  1. Students will find water used by subtracting a starting meter reading from an ending reading.
  2. Students will calculate gallons used per person each day and compare it to a common benchmark.

Vocabulary

Water meter
A device that measures how much water a home or business uses so the utility can bill fairly. Reading the meter can also reveal hidden leaks.

Also: reading, per person per day, benchmark

Teacher overview

Reading the water meter is a practical consumer skill: it lets a household see how much water it actually uses and check that number against a normal range. This lesson uses the Okafor family, a fictional household of four, and their weekly meter readings. Students subtract the readings to find the water used, divide to find gallons used per person each day, compare that figure to a common benchmark, and then set a percent savings goal for the next week. A common misconception this lesson corrects is that the meter shows how much water is left; instead, the meter counts up, so use is always the difference between two readings.

For reference, the average US household uses about 300 gallons of water a day, roughly 70 percent of it indoors, and the USGS estimates that each person in the United States uses about 80 to 100 gallons of water a day at home.

Procedure

Hook (5 min): Project a picture of a water meter reading 51,204.3 and ask what the number means. Guide students to see that it counts total gallons since the meter was installed, not the water left in the pipes.

Direct instruction and worked example (12 min): Give the Okafor family's readings for the week. The meter read 51,204.3 gallons on Monday morning and 53,444.3 gallons the next Monday. Model the steps. Water used: 53,444.3 minus 51,204.3 equals 2,240.0 gallons for the week. Per day: 2,240 divided by 7 equals 320 gallons a day. Per person each day: 320 divided by 4 people equals 80 gallons per person each day, which sits at the low end of the common benchmark of 80 to 100 gallons per person each day at home. Then set a goal: the family wants to cut daily use by 15 percent, so the new target is 320 times 0.85, which is 272 gallons a day. These three results are problems 1 through 3 on the student handout, and students copy each step as it is modeled.

Guided practice (13 min): In pairs, students work problems 4 through 6 on the handout, using the next week's readings of 53,444.3 on Monday and 55,404.3 the following Monday. They find the water used, the gallons per person each day, and the percent decrease from 320 to the new daily amount. Circulate and confirm pairs subtract the readings in the correct order.

Independent practice (10 min): Each student completes problems 7 through 9 on the handout's meter-reading slip, using new decimal readings and a decimal savings factor.

Closure and exit ticket (5 min): Students answer problem 10, the exit ticket: "A family of 5 uses 500 gallons in one day. How many gallons is that per person?" Collect and scan for the correct division. If several students multiply instead, reteach the per-person step next class.

The Okafor Family's Water Meter: A Grade 6 Home-Use Lesson — Grade 6 Health & Consumer Science
Name: ____________________________ Date: ______________

Student Handout

Work the problems in order and show the arithmetic you use. Label each answer in gallons or as a percent. The Okafor family has four people, and each weekly reading is taken on a Monday morning.

Worked example week

  1. The meter read 51,204.3 gallons on Monday and 53,444.3 gallons the next Monday. How many gallons did the family use during the week?
  2. The family used 320 gallons a day that week. For the four-person household, how many gallons per person each day is that?
  3. The family wants to cut its daily use of 320 gallons by 15 percent. Multiply 320 by 0.85 to find the new daily target in gallons.

The next week

  1. The meter read 53,444.3 gallons on Monday and 55,404.3 gallons the following Monday. How many gallons did the family use during the week?
  2. That week the family used 1,960 gallons over 7 days. Divide by 7, then by 4 people, to find the gallons per person each day.
  3. The family's daily use fell from 320 gallons to 280 gallons. What is the percent decrease?

Meter-reading slip

  1. The slip shows 41,200.5 gallons on Monday and 42,880.5 gallons the next Monday. How many gallons did the family use during the week?
  2. That week the family used 1,680 gallons over 7 days. Divide by 7, then by 4 people, to find the gallons per person each day.
  3. The family used 240 gallons a day that week and wants to cut it by 15 percent. Multiply 240 by 0.85 to find the new daily target in gallons.

Exit ticket

  1. A family of 5 uses 500 gallons in one day. How many gallons is that per person?

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: 2,240 gallons. Worked example: 53,444.3 minus 51,204.3 equals 2,240.0 gallons used in the week.
  2. Answer: 80 gallons. Worked example: 320 gallons a day divided by 4 people equals 80 gallons per person each day.
  3. Answer: 272 gallons. Worked example: 320 gallons a day times 0.85 equals a 272-gallon daily target after a 15 percent cut.
  4. Answer: 1,960 gallons. Guided practice: 55,404.3 minus 53,444.3 equals 1,960.0 gallons used in the week.
  5. Answer: 70 gallons. Guided practice: 1,960 divided by 7 is 280 a day, and 280 divided by 4 people is 70 gallons per person each day.
  6. Answer: 12.5 percent. Guided practice: use fell from 320 to 280 a day, a drop of 40, and 40 divided by 320 equals 0.125.
  7. Answer: 1,680 gallons. Independent practice: 42,880.5 minus 41,200.5 equals 1,680.0 gallons for the week.
  8. Answer: 60 gallons. Independent practice: 1,680 divided by 7 is 240 a day, and 240 divided by 4 people is 60 gallons per person each day.
  9. Answer: 204 gallons. Independent practice: a 240-gallon day times 0.85 equals a 204-gallon target after a 15 percent cut.
  10. Answer: 100 gallons. Exit ticket: 500 gallons divided by 5 people equals 100 gallons per person.

Differentiation

Support

Provide a labeled subtraction frame with the ending reading already above the starting reading, lined up by place value, and let students use a calculator for the division steps. Work the first per-person division together before students try the rest.

Extension

Ask students to figure out how many gallons per person each day the family would reach if it cut use by 25 percent instead of 15 percent, and to explain in writing why a smaller per-person number is not automatically better if the household has more people.

ELL supports

Pre-teach "meter," "reading," and "per person" with a simple picture of a dial counting up. Provide a sentence frame for comparing to the benchmark: "The family used ___ gallons per person. That is below or above the usual 80 to 100 gallons used at home."