Writing prompt Grade 8 English Language Arts
Basalt Crossing's Bioswales: A Grade 8 Informative Writing Prompt
A grade 8 informative writing prompt where students explain how a fictional town's new bioswales reduce flooding and pollution using cause-effect structure.
Objectives
- Students will write an informative essay that explains a process using organized, cause-and-effect structure.
- Students will use precise stormwater vocabulary to convey how green infrastructure reduces flooding and pollution.
Vocabulary
- Stormwater
- Stormwater is rain or melted snow that flows off roofs, streets, and parking lots. In most towns it goes into storm drains and flows to a stream without being treated, carrying whatever it picked up.
- Bioswale
- A bioswale is a wide, shallow, plant-lined channel that slows down stormwater and lets it soak in as it moves. You often see bioswales along parking lots and streets.
- Impervious surface
- An impervious surface is any hard surface, like a road, roof, or parking lot, that rain cannot soak through. The more impervious surface a town has, the more stormwater rushes off it.
- Green infrastructure
- Green infrastructure uses soil and plants, like rain gardens, green roofs, and street trees, to soak up rainwater where it falls instead of piping it away. It copies the way nature handles rain.
Also: runoff
Teacher overview
Basalt Crossing (a fictional town used for this prompt) installed a series of bioswales along Main Street to address two problems at once: flooding after heavy rain and polluted runoff reaching Basalt Creek downstream. This prompt asks students to explain, in an organized informative essay, how a single piece of green infrastructure can address two separate problems through one underlying process.
Prompt
Background: Basalt Crossing is a fictional town used for this prompt. For years, it has struggled with flooding on Main Street after heavy rain. Polluted runoff has also reached Basalt Creek downstream. Like many older downtowns, Main Street is covered mostly in pavement. Pavement is an impervious surface, which means rain cannot soak into it. Engineers use a runoff coefficient to estimate how much water a storm sends rushing off a surface. A paved surface can send back roughly 0.9 of the rain that falls on it as runoff. A grassy lawn sends back only about 0.2. That difference explains why Main Street's storm drains kept overflowing. Nearly all the rain that fell on the pavement had nowhere to go but straight into the pipes at once.
Last year, the town installed a series of bioswales. A bioswale is a shallow, planted channel built along the edge of a sidewalk. Instead of routing rainwater directly into a pipe, a bioswale captures runoff and slows it down. The water then soaks into the ground through layers of soil, gravel, and plant roots. As the water moves slowly through those layers, plants and soil naturally filter out oil, sediment, and other pollutants. Before the bioswales, those pollutants washed off the pavement and straight into Basalt Creek.
Writing task: Basalt Crossing's town newsletter wants an article about the new bioswales. The article should explain how they work and why they solve two problems, flooding and pollution, at once. Write an informative essay that explains this process. Use specific details and vocabulary from the background material above. Organize your essay so a reader can follow each step of the process in order.
Planning Organizer
| Category | Your notes |
|---|---|
| Topic sentence: what problem(s) does a bioswale solve? | |
| Step 1: what happens to rainwater first? | |
| Step 2: what happens as water moves through the bioswale? | |
| Step 3: what is the result for flooding? | |
| Step 4: what is the result for pollution? | |
| Precise vocabulary to include (at least three terms) | |
| Concluding statement |
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Exemplar & Rubric
Exemplar response:
Basalt Crossing's new bioswales solve two problems at once: flooding on Main Street and pollution reaching Basalt Creek downstream. Both problems trace back to the same cause, pavement. A paved surface sends back roughly 0.9 of the rain that falls on it as runoff, compared to about 0.2 for a grassy lawn, which means nearly all the rain that fell on Main Street's pavement used to rush directly into the storm drains at once, overwhelming the pipes during heavy storms.
A bioswale changes what happens to that rainwater from the very first moment it hits the ground. Instead of flowing straight into a storm drain, runoff from the street flows into the bioswale, a shallow, planted channel built along the edge of the sidewalk. There, the water slows down and begins soaking into the ground through layers of soil, gravel, and plant roots rather than continuing on as a fast-moving sheet of runoff. That slowing effect is what reduces flooding: water that soaks gradually into the ground never reaches the storm drains at the same overwhelming volume and speed it used to.
The same slow soaking process also reduces pollution. As stormwater moves through the bioswale's soil and plant roots, oil, sediment, and other pollutants that had washed off the pavement get filtered out naturally, the way soil and roots trap and break down material moving through them. Water that eventually reaches Basalt Creek has already passed through that natural filter, instead of carrying Main Street's pollutants directly into the water. By slowing runoff and filtering it at the same time, a single bioswale addresses both of Basalt Crossing's problems using the same simple process.
Rubric:
| Criterion | Emerging | Developing | Proficient | Advanced |
|---|---|---|---|---|
| Organization | Ideas appear in no clear order | Ideas are grouped but the process sequence is unclear | Explains the bioswale process in a clear, logical sequence | Explains the process in a clear sequence and explicitly connects each step back to flooding or pollution |
| Content & vocabulary | Little specific content; vague or missing vocabulary | Some background details used; vocabulary used loosely or incorrectly | Uses specific details and at least two precise vocabulary terms accurately | Uses specific details and three or more precise vocabulary terms accurately and purposefully |
| Development | Does not explain how the process addresses both flooding and pollution | Explains how the process addresses one of the two problems | Explains how the process addresses both flooding and pollution | Explains both problems and how the single underlying cause, the impervious pavement, connects them |
| Conventions | Frequent errors interfere with meaning | Noticeable errors that do not block meaning | Few errors; clear sentences | Virtually error-free; sentences vary in structure for clarity |
Differentiation
Support (below grade level)
Provide a four-box sequence chart (Rain falls on pavement → Runoff enters bioswale → Water slows and soaks in → Result for flooding and pollution) with the first box completed as a model, along with a word bank of the background material's key vocabulary.
Extension (above grade level)
Ask students to research (using only the background material provided, not outside sources) why a grassy lawn's lower runoff coefficient, about 0.2 compared to pavement's 0.9, makes it act somewhat like a natural bioswale, and add a paragraph comparing the two.
ELL supports
Pre-teach "impervious surface," "runoff," "bioswale," and "filter" with a simple before-and-after diagram of rain hitting pavement versus rain hitting a planted channel. Allow the Planning Organizer to be completed with phrases rather than full sentences before drafting begins.