Lesson plan Grade 8 English Language Arts
How Cinderpath Cleans Its Water: A Grade 8 Process-Writing Lesson
A grade 8 ELA lesson where students order the steps a treatment plant uses and write an informative process paragraph explaining how Cinderpath makes water safe.
Objectives
- Students will place the steps of drinking-water treatment in the correct order and explain the purpose of each.
- Students will write an informative paragraph that uses transition words to explain the treatment process clearly.
Vocabulary
- Coagulation
- Coagulation is the first cleaning step at a drinking water plant. Operators quickly mix in a chemical that makes tiny bits of dirt stop pushing each other away so they can start sticking together.
- Sedimentation
- Sedimentation is the step where water sits almost still in a big basin so the heavy clumps of dirt can sink to the bottom. The cleaner water on top then moves on to the filters.
- Filtration
- Filtration is the step where water passes through layers of sand, gravel, or other materials that trap the small particles still left in it. It works like a very fine strainer.
- Disinfection
- Disinfection is the step that kills or disables germs in water so it is safe to drink. Water plants usually disinfect with chlorine, ultraviolet light, or ozone.
- Turbidity
- Turbidity is a measure of how cloudy or murky water looks because of tiny particles floating in it. Clear water has low turbidity, and muddy water has high turbidity.
Teacher overview
Cinderpath is a fictional city whose treatment plant turns cloudy reservoir water into safe drinking water through a sequence of steps. This lesson has students order those steps and then write an informative paragraph that explains the process to a reader who has never seen a treatment plant. Grade 8 writers often list steps without connecting them, so the lesson focuses on transition words and on stating the purpose of each step, not just its name.
Procedure
Hook (5 min): Show students a jar of muddy water and a glass of clear tap water. Ask what would have to happen to the muddy water to make it safe to drink. Record their guesses for comparison with the handout.
Read the process (12 min): Students read the Cinderpath treatment description on the Student Handout, underlining the name of each step and the reason it is done. Point out that the plant measures its success with turbidity, a number that describes how cloudy the water is.
Model process language (10 min): On chart paper, model turning two steps into connected sentences using transition words such as "first," "next," "after that," and "finally." Show how naming the purpose ("so that the heavy clumps settle out") makes the explanation clearer than the step name alone.
Sequence check, formative (10 min): In pairs, students cut the six steps from the handout into cards, place them in order, and answer the comprehension questions on the handout. Circulate and confirm each pair can state why disinfection comes near the end. This is the formative checkpoint: pairs who reverse filtration and disinfection get a targeted prompt before drafting.
Draft the paragraph (13 min): Each student writes one informative paragraph that walks a reader through the six steps in order, using at least three transition words and naming the purpose of each step. The ordered cards and the purposes students underlined feed the draft directly.
Exit ticket (5 min): Students write one sentence explaining why the plant checks turbidity, and one sentence naming the last step before water leaves the plant. Collect and scan before dismissal.
Student Handout
How the Cinderpath plant treats water. The Cinderpath Water Treatment Plant draws about 4 million gallons of water each day from Mossgate Reservoir. Reservoir water is cloudy because it carries tiny bits of clay, algae, and dirt. Cloudiness is measured as turbidity, and federal rules require finished water to stay at or below 0.3 NTU in almost all samples. The plant reaches that goal through six steps, listed below out of order.
- Filtration: the water passes down through layers of sand and gravel that trap the smaller particles left behind.
- Storage and distribution: the finished water is held in a covered tank and then sent through the mains to homes.
- Coagulation: workers add a chemical that makes the tiny particles stop pushing apart and start sticking together.
- Disinfection: the plant adds chlorine to kill germs, keeping a small residual of about 0.2 to 2.0 mg/L so the water stays protected in the pipes.
- Sedimentation: the water slows down in a large basin so the heavy floc settles to the bottom.
- Flocculation: gentle paddles stir the water so the sticky particles bump into each other and form larger clumps called floc.
Comprehension and sequencing. Answer in complete sentences.
- Put the six steps in the correct order from the raw reservoir water to the tap.
- Why does sedimentation work better after coagulation and flocculation than it would on the raw water alone?
- What does the turbidity number tell the operators about the water?
- Why is disinfection placed near the end of the process rather than at the beginning?
- Why does the plant keep a small chlorine residual in the water even after it leaves the plant?
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: Coagulation, flocculation, sedimentation, filtration, disinfection, then storage and distribution.
- Answer: Coagulation and flocculation make the tiny particles clump into heavier floc, and heavier clumps settle out of the water faster, so sedimentation removes much more than it could from raw water.
- Answer: Turbidity tells operators how cloudy the water is, which shows how much particle material remains; lower turbidity means the earlier steps removed more material.
- Answer: Disinfection comes near the end so the earlier steps first remove particles that could shield germs from the chlorine, which lets the disinfection work on cleaner water.
- Answer: A small residual of about 0.2 to 2.0 mg/L keeps killing germs as the water travels through the mains, protecting it between the plant and the home.
Differentiation
Support
Provide the six step cards already labeled with both the step name and its purpose, so students focus on ordering and on the transition words rather than on recalling each step. Offer a transition-word bank for the paragraph.
Extension
Ask students to add one sentence explaining what would likely happen to the finished-water turbidity if the filtration step were skipped, using the purpose of filtration as their reasoning.
ELL supports
Pre-teach "coagulation," "sedimentation," "filtration," "disinfection," and "turbidity" with a labeled diagram of the plant showing each basin. Allow the sequencing task to be completed by arranging cards before writing full sentences.
Extensions
Have students revise their paragraph into a short set of numbered instructions for a poster in the school hallway, keeping the purpose of each step but shortening the wording for a general audience.