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Lesson plan Grade 3 Science

Where Ollerton's Sink Water Goes: A Grade 3 Wastewater Lesson

A 45-minute grade 3 lesson tracing used water from a school sink to a made-up town's cleaning plant, with criteria, limits, and minute-level tank times.

Objectives

  1. Students will trace the path used water takes from a sink to a cleaning plant.
  2. Students will state one goal and one limit for the town's cleaning plant.
  3. Students will find minute-level time intervals between tank steps.

Vocabulary

Key words: drain, sewer pipe, screen, settling tank, microbe, outfall

Teacher overview

Water that leaves a classroom sink travels through a sewer pipe to a plant where screens, tanks, and microbes clean it before it returns to a stream. This lesson follows that path in the fictional town of Ollerton, whose plant sends its finished water to Pinkerly Brook, and asks students to name what the water must do before it is allowed back into the brook and what limits the crew works under. The misconception worth planning for is the common belief that a sink drain and a street storm drain lead to the same pipe; in most towns they do not, and only the sink water reaches the cleaning plant. Students also tend to think used water simply goes away, so the yarn walk keeps the whole route visible in one piece.

Procedure

Hook (5 min): Ask students where the water goes after they wash their hands. Take three or four answers and write them on chart paper. Then hold up one end of the yarn at a classroom sink and say that the class is going to lay out the whole route.

Yarn walk and sequencing (12 min): Stretch the yarn across the front of the room. Place the five labeled cards along it in order: sink, sewer pipe, screen room, settling tank, bubble tank. Add a sixth stop, the outfall at Pinkerly Brook, at the far end. Ask students what each stop takes out. Move one card out of order and ask the class to catch the error and explain why that order would fail.

Direct instruction (8 min): Explain that the screen room catches rags and sticks, the settling tank lets the heavy solids sink, and the bubble tank feeds air to microbes that eat what is dissolved in the water. Name the goals the finished water must meet at the outfall: clear enough to see through, free of floating solids, and carrying enough oxygen for fish. Then name the limits the fictional Ollerton crew works under, which are room for only two large tanks and a single work shift to move a batch through.

Handout work (12 min): Distribute the handout and read the tank schedule aloud once. Students complete items 1 through 7 on their own. Use the demonstration clock to model item 2 for the whole class before releasing them, since finding a later time from a start time and a duration is the step most students miss.

Closure and formative check (8 min): Ask every student to write one goal and one limit for the Ollerton plant on an exit slip. Collect the slips and sort them into two piles at the door. If more than a quarter of the class puts a goal in the limit column, reteach the difference with two fresh examples before the next lesson.

Where Ollerton's Sink Water Goes: A Grade 3 Wastewater Lesson — Grade 3 Science
Name: ____________________________ Date: ______________

Student Handout

Ollerton is a made-up town. Water from its sinks and tubs runs down drains into a sewer pipe. The pipe carries the water to the town plant. The plant cleans the water. Then the water goes back into Pinkerly Brook.

The plant moves one batch of water through three stops. Here is the schedule for one batch.

Stop Time in Time out
Screen room 9:10 9:25
Settling tank 9:25 stays 40 minutes
Bubble tank 10:05 11:00
  1. Water goes into the screen room at 9:10. It comes out at 9:25. How many minutes was it in the screen room?
  2. Water goes into the settling tank at 9:25. It stays 40 minutes. What time does it come out?
  3. Water goes into the bubble tank at 10:05. It comes out at 11:00. How many minutes was it in the bubble tank?
  4. The screen room took 15 minutes. The bubble tank took 55 minutes. How many minutes is that in all?
  5. Write one thing the cleaned water must do before the plant lets it go into Pinkerly Brook.
  6. The Ollerton plant has room for only two big tanks. Is that a goal or a limit? Tell why.
  7. Name one thing that should never go down a sink drain at your school.

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: 15 minutes. Count from 9:10 to 9:25, which is 15 minutes.
  2. Answer: 10:05. Start at 9:25 and count on 40 minutes: 35 minutes brings you to 10:00, and 5 more minutes brings you to 10:05.
  3. Answer: 55 minutes. Count from 10:05 to 11:00, which is 55 minutes.
  4. Answer: 70 minutes. Add the two stops: 15 plus 55 is 70.
  5. Answer: Accept any goal named in the lesson or a reasonable equivalent, including that the water must be clear enough to see through, must carry no floating solids, must not smell, or must hold enough oxygen for the fish in the brook.
  6. Answer: A limit. Accept any explanation stating that the room for two tanks is something the crew cannot change, so it holds the design back, while a goal is something the finished water has to achieve.
  7. Answer: Accept any item that clogs pipes or harms the microbes, including cooking grease, wipes, paper towels, paint, glue, or sand from an art tray. A student who names something harmless, such as hand soap, should be asked what happens to grease when it cools inside a pipe.

Differentiation

Support

Give these students a number line printed in five-minute marks so items 1 through 4 become counting-on tasks. Provide the six route cards face up in a scrambled row and let them rebuild the order by hand before writing. For item 6, offer a two-choice box labeled goal and limit rather than an open response.

Extension

Have students redraw the Ollerton schedule for a day when twice as much water arrives, doubling only the settling time, and then argue in writing whether the batch still finishes inside one work shift. Ask them what the crew could change if it does not, and which of their ideas the two-tank limit rules out.

ELL supports

Pre-teach "drain," "tank," and "screen" using the labeled cards and the yarn route. Model reading the schedule table row by row with a finger. Provide the frames "The water was in the ___ for ___ minutes" and "This is a ___ because the crew cannot change it," and allow item 5 to be answered with a labeled drawing of the brook.

Extensions

Walk the class outside to find a storm drain and a sanitary sewer cover in the same block, keeping the group on the sidewalk with adult supervision and leaving every cover closed, then return and add both to the yarn route as separate paths. Ask students to write one sentence explaining which path carries water to the cleaning plant and which carries water straight to a stream.