Lesson plan Grade 5 Health & Consumer Science
Reading a Family's Water Meter: A Grade 5 Consumer Skills Lesson
A 45-minute grade 5 lesson that pairs decimal subtraction and division on realistic water meter readings with a short discussion of hydration.
Objectives
- Students will subtract two decimal meter readings to calculate a household's monthly water usage in gallons.
- Students will divide monthly usage by the number of days in a billing period to find average daily use.
- Students will compare a family's daily water use to the national household average and explain why staying hydrated during physical activity matters.
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: usage, average, hydration
Teacher overview
A water meter quietly records a household's total water use, and comparing two meter readings, one from last month and one from this month, is a practical consumer skill that depends on the same decimal subtraction and division students are learning in fifth grade. This lesson pairs that consumer-math task with a short discussion of hydration, since drinking enough water is especially important on days with recess, PE, or sports practice, alongside a look at each student's own daily water needs.
A common error in this lesson is subtracting the readings in the wrong order or forgetting to line up decimal places correctly, which produces a usage total that looks reasonable but is actually wrong; the guided practice example walks through lining up the decimals step by step to head off that mistake.
Procedure
Hook (5 min): Ask students to guess how many gallons their own household might use in a single day. Take a few guesses aloud without correcting them yet, then explain that a real water meter keeps a running total, and today's lesson is about figuring out actual usage from two readings, the same way a family or a meter technician would.
Direct instruction (10 min): Explain that a water meter shows a cumulative total, meaning it keeps adding up rather than resetting each month, so finding a month's usage means subtracting last month's reading from this month's reading. Introduce the hydration connection: our bodies lose water through sweat, especially during exercise, so drinking water regularly before, during, and after PE or sports practice replaces what the body loses. Drinking water is only a small part of a household's total use; most of the water a meter records goes to toilets, showers, laundry, and outdoor watering.
Guided practice (10 min): Work through the Nguyen family's readings together on the board. Last month's meter reading was 84,215.6 gallons, and this month's reading is 87,940.2 gallons. Subtract to find usage: 87,940.2 − 84,215.6 = 3,724.6 gallons. Then divide by the 30 days in the billing period: 3,724.6 ÷ 30 ≈ 124.2 gallons per day. Compare that to the fact that the average US household uses about 300 gallons of water per day: the Nguyen family used about 175.8 gallons less per day than that national average.
Independent practice (15 min): Students complete the handout with the Alvarez family's readings on their own: last month's reading was 61,050.4 gallons, and this month's reading is 64,900.9 gallons. Students subtract to find the month's usage, divide by 30 days to find the daily average, and compare that average to the 300-gallon national figure, stating whether the Alvarez family used more or less water per day than average and by about how much.
Closure / exit ticket (5 min): Students answer one question on an index card: "A family's meter read 52,300.0 gallons last month and 54,150.5 gallons this month. How many gallons did the family use?" Collect the cards and scan for the correct subtraction method 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
Answer: 3,850.5 gallons (Alvarez family monthly usage).
64,900.9 − 61,050.4 = 3,850.5 gallons.Answer: 128.35 gallons per day, about 172 gallons less than the national average.
3,850.5 ÷ 30 = 128.35 gallons per day. 300 − 128.35 = 171.65, which rounds to about 172 gallons less per day than the national average of about 300 gallons per day.Answer: 1,850.5 gallons (exit ticket).
54,150.5 − 52,300.0 = 1,850.5 gallons.
Differentiation
Support (below grade level)
Provide the Nguyen family's subtraction already set up with decimal places aligned in a vertical format, so students focus on the division step during guided practice. For independent practice, give the Alvarez family's subtraction pre-aligned in the same vertical format and allow a calculator for the division step.
Extension (above grade level)
Ask students to figure out, using the Alvarez family's daily average, about how many gallons that family would use over an entire year (365 days), and compare that yearly total to the national household average scaled up the same way.
ELL supports
Pre-teach meter, usage, and average with a simple visual, such as a dial or digital display showing two different numbers side by side with an arrow labeled "difference" between them. Allow students to show the subtraction and division steps using numbers and a labeled diagram rather than writing a full sentence explanation for the comparison to the national average.