Reading passage Grade 3 English Language Arts
The Tiny Cleaners in Stonewhistle's Water Tanks
A grade 3 informational passage about the microbes that do the real work at a used-water plant, with seven questions that mix stated facts and inference.
Objectives
- Students will answer questions about an informational passage using details stated in the text.
- Students will explain why the plant sends the clumps of microbes back to the first tank.
- Students will use the passage to say what a healthy tank looks like under a microscope.
Vocabulary
Key words: microbe, blower, clump, microscope, tank
Teacher overview
This passage describes the fictional town of Stonewhistle and the living part of its water cleaning plant, where microbes eat the waste that screens and settling cannot remove. It gives third graders an informational text with a clear cause-and-effect spine and one worker's job to anchor it. The misconception most worth naming beforehand is that anything alive in water must be harmful, and the passage answers it by showing a plant operator whose work is keeping the microbes healthy rather than getting rid of them.
Passage
The Tiny Cleaners in Stonewhistle's Water Tanks
The town of Stonewhistle has a plant that cleans the water people have already used. Water comes to the plant from sinks, showers, and washing machines. It leaves clean enough to flow back into the river. The biggest job at that plant is not done by a machine. It is done by living things too small to see.
These tiny living things are called microbes. Millions of them live in one spoonful of tank water. Microbes eat the bits of food, soap, and waste that are still floating in the water. What people wash down the drain is what the microbes live on.
Microbes need three things to do their work: food, air, and time. The food is already in the water when it arrives. The air comes from blowers under the tank. The blowers push bubbles up through the water all day, and the tank rolls and hisses like a pot about to boil. Time comes from the size of the tank. The water sits there for hours before it moves on.
Ms. Whitlow runs the plant. She says her job is a lot like farming. She does not tell the microbes what to do. She keeps them comfortable. If the water turns too cold, they slow down. If the air stops, many of them die, and the plant cannot clean the water until new ones grow.
When the microbes finish eating, they clump together. The clumps are heavier than water, so they sink to the bottom of the next tank. That leaves clear water on top, and the clear water flows on to the last step. The clumps do not go to the trash. A pump sends most of them back to the first tank, where they start eating again.
Once a week, Ms. Whitlow puts a drop of tank water under a microscope. She looks for tiny animals that swim in circles. When she sees plenty of them, she knows the tank is healthy. When she sees very few, she knows something is wrong, and she checks the blowers first.
Questions
- Where does the water that comes into the Stonewhistle plant come from?
- What do the microbes eat?
- What three things do microbes need to do their work?
- Where does the air in the tank come from?
- Why does Ms. Whitlow say her job is a lot like farming?
- Why does a pump send most of the clumps back to the first tank?
- Ms. Whitlow looks at a drop of tank water under a microscope. What does she think when she sees very few tiny animals swimming?
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: From sinks, showers, and washing machines. The first paragraph lists all three.
- Answer: The bits of food, soap, and waste still floating in the water. The second paragraph states this.
- Answer: Food, air, and time. The third paragraph names them in that order.
- Answer: From blowers under the tank. The passage says the blowers push bubbles up through the water all day.
- Answer: Because she keeps the microbes comfortable instead of telling them what to do, the way a farmer cares for living things rather than running a machine.
- Answer: So the microbes can start eating again. Accept answers explaining that the plant keeps enough microbes working instead of throwing living helpers away.
- Answer: That something is wrong in the tank. The passage says she checks the blowers first, because the microbes need air.
Differentiation
Support
Read the passage aloud once before students read it themselves, and give these students a copy with the three needs of microbes already underlined. Allow questions 5 through 7 to be answered out loud to a partner who writes the answer down.
Extension
Ask students to write the three sentences Ms. Whitlow would put in her log book on a day when the blowers stopped for an hour, using only what the passage says would happen. They should mark which sentence explains the cause and which explains the effect.
ELL supports
Pre-teach "microbe," "blower," and "clump" with a picture card for each, and demonstrate clumping by dropping a pinch of flour into a cup of water and stirring until it gathers. Provide frames for questions 5 and 6: "Her job is like farming because ___," and "The pump sends them back so ___."
Extensions
Students can compare this passage with the classroom's own observations of a jar of pond water left on a windowsill, listing what they can see and what the passage says they would need a microscope to see. The comparison sets up later work on evidence that requires a tool to collect. An adult collects the pond water, and the jar stays closed so no one touches or drinks it.