A Meter Technician's Route in Bexholme: Finding Hidden Leaks

Hook (5 min). Project a photograph or sketch of a residential water meter with the number 45,900 on its register. Ask the class what that number means. Collect two or three answers without correcting them yet. Tell students that by the end of the period they will know why that number alone cannot tell anyone whether a family is wasting water.

Direct instruction on the job (10 min). Explain that a meter technician in the town of Bexholme installs, tests, replaces, and reads the meters that measure how much water each building uses. On a normal day the technician swaps out meters that have stopped counting, checks meters that read far higher or far lower than the neighbors, tests a meter's accuracy against a known volume of water, and flags accounts with unusual use for a follow-up visit. The path in usually starts with a high school diploma and on-the-job training, and many utilities pay for a short meter or backflow certification course. Some technicians move on to a state operator license, a two-year college program, or a four-year engineering degree, and the sector treats all of those routes as legitimate.

Teacher-modeled worked example (10 min). Work this example on the board while students watch, and tell them explicitly that this one is modeled for them and is not on their handout. A house on Durling Lane in the town of Bexholme read 17,250 gallons on the first day of the month and 20,250 gallons on the thirty-first day. Subtract to find use: 20,250 minus 17,250 equals 3,000 gallons. Divide by the number of days: 3,000 divided by 30 equals 100 gallons per day. Say the unit rate aloud in words, then ask the class the check-for-understanding question: if a second house shows a difference of 6,000 gallons over the same 30 days, is its daily rate higher or lower than 100 gallons per day? Take a thumbs-up or thumbs-down poll, and reteach the division step if more than five students answer incorrectly.

Student Handout practice (18 min). Distribute the handout. Students work questions 1 through 7 alone or in pairs. Circulate and watch for two specific errors: dividing by 31 instead of 30, and dividing the days by the gallons instead of the gallons by the days. For question 5, remind students that a percent decrease compares the drop to the starting amount, not to the ending amount.

Debrief and exit ticket (7 min). Ask which house on the handout a technician should visit first and why. Steer the discussion toward the fact that a high total is not by itself evidence of a leak, while a sudden jump in the daily rate usually is. Collect question 7 as the exit ticket. Students who explain that the daily rate lets houses with different reading dates be compared have met the objective.