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Reading passage Grade 7 English Language Arts

A Class Tour of the Harkness Mill Water Cleaning Plant

A grade 7 informational passage narrating a class visit to a fictional wastewater plant, tracing how dirty water is cleaned before it returns to the river.

Objectives

  1. Students will identify the stages that clean water at a wastewater plant, in order.
  2. Students will infer why living microbes are central to cleaning the water.

Vocabulary

Wastewater
Wastewater is used water from sinks, showers, toilets, and businesses that goes down the drain. It travels through sewer pipes to a treatment plant to be cleaned before returning to nature.
Aeration
Aeration means mixing air into water. At a wastewater plant, blowers bubble huge amounts of air through tanks so the helpful microbes have the oxygen they need to eat the waste.

Also: microbes, settling tank

Teacher overview

This passage follows a seventh grader on a class tour of a fictional wastewater plant. It explains, stage by stage, how the water that leaves sinks and drains gets clean enough to return to a river. The text is written to be read closely, since the questions ask students to trace the order of the stages and to infer why the plant depends on living microbes. It pairs well with a unit on how communities protect the water they share.

A Class Tour of the Harkness Mill Water Cleaning Plant — Grade 7 English Language Arts
Name: ____________________________ Date: ______________

Passage

Our class met Ms. Ortega at the gate of the Harkness Mill plant. She told us the plant cleans wastewater. Wastewater is the used water that leaves sinks, showers, toilets, and drains all over town. It travels through underground pipes to this one place. "Everything you rinse down a drain ends up here," she said. "Our job is to make it clean before it goes back to the river."

The first stop was loud and smelled sharp. Bar screens, like giant combs, caught trash from the water. Wipes, sticks, and plastic piled up on the metal bars. "People flush things they should not," Ms. Ortega said. "The screens protect our pumps." Without this step, she explained, the trash would clog the machines further along.

Next we walked to a wide, round tank. The water here moved slowly. Ms. Ortega called it a settling tank. When the water slows down, the heavy solids sink to the bottom. A slow-moving arm scraped the sludge toward a drain in the center. The water that flowed out of the top was cleaner, but it was not clean yet. Tiny bits of waste were still mixed in, too small to see.

Then came the part I did not expect. We reached long tanks full of bubbling water. The bubbles were air, pumped in from below. This step is called aeration. "The water is full of microbes here," Ms. Ortega said. Microbes are living things too small to see. In these tanks, the microbes eat the waste still floating in the water. The air keeps the microbes alive and active. The more they eat, the cleaner the water becomes. I had thought a plant cleaned water with chemicals and filters only. I had not pictured living helpers doing the work.

After the microbes finished, the water flowed to a second settling tank. Here the clumps of microbes sank to the bottom, just as the heavy solids had earlier. Some of these microbes were pumped back to the bubbling tanks to keep working. The clear water on top moved on to the last step.

At the final stage, the plant added a small dose of disinfectant. This killed any germs still left. Ms. Ortega showed us a sample in a glass jar. It looked as clear as tap water, though she reminded us it was not for drinking. Workers test the water every day. It has to meet a strict limit before it can leave. Only then does the cleaned water flow back into the river.

On the bus ride home, I kept thinking about the bubbling tanks. The plant did use screens, tanks, and disinfectant. But the real cleaning came from millions of tiny living things doing a job for the whole town.

Questions

  1. According to the passage, what is wastewater, and where does it come from?
  2. Cite two details from the passage that explain what the bar screens do and why that step matters.
  3. What happens to the heavy solids in the first settling tank?
  4. In the aeration tanks, what do the microbes do, and why is the pumped-in air important? Use the passage.
  5. The narrator says the "real cleaning" comes from living things. Cite evidence from the passage that supports this idea.
  6. Why do you think the plant tests the water every day before letting it leave? Support your inference with the passage.

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: Wastewater is the used water that leaves sinks, showers, toilets, and drains around town. It travels through underground pipes to the plant, as the passage states near the beginning.
  2. Answer: The bar screens catch trash such as wipes, sticks, and plastic, and they protect the plant's pumps. The passage says the trash would clog the machines without this step.
  3. Answer: The heavy solids sink to the bottom when the water slows down, and a slow-moving arm scrapes the sludge toward a center drain. The passage describes this in the settling-tank paragraph.
  4. Answer: The microbes eat the waste still floating in the water, and the pumped-in air keeps them alive and active so they keep eating. The passage links the air to the microbes staying active.
  5. Answer: Answers will vary but should cite the aeration paragraph, where microbes eat the waste, and the closing line that the real cleaning came from millions of tiny living things. Two details support the idea.
  6. Answer: Answers will vary. A strong inference notes that the water returns to a shared river, so daily testing makes sure it meets the strict limit and is truly clean before release. The paragraph about the final stage supports this.

Differentiation

Support

Provide a five-box flow strip (screens, settling, aeration, second settling, disinfection) for students to label as they read, and allow them to answer questions 1 and 3 with short phrases and a paragraph reference.

Extension

Ask students to write a short paragraph explaining what would happen to the river if the aeration step failed and the microbes died, using details from the passage to support the cause and effect.

ELL supports

Pre-teach "wastewater," "microbes," and "aeration" with simple pictures. Allow students to point to the stage in the flow strip before writing, and provide the sentence frame "The passage says ___, which shows ___" for the citing questions.