Graphic organizer Grade 8 English Language Arts
Evidence Frames for the Shelvock Upper Pressure Zone
A grade 8 four-column organizer that walks students from lead-in to evidence to explanation to link while building an explanatory paragraph about water pressure.
Objectives
- Students will introduce evidence with a lead-in instead of dropping a quotation into a paragraph.
- Students will explain how each piece of evidence supports the paragraph's point.
- Students will link one piece of evidence to the next with a stated connection.
Vocabulary
- Pressure zone
- A pressure zone is a section of a water system that a utility manages separately because it sits at a different elevation than the rest of the town. Utilities create pressure zones so that water pressure stays safe and steady for everyone, whether they live at the bottom of a hill or near the top.
Also: lead-in, paraphrase, booster pump, head, transition
Teacher overview
This four-column frame moves a writer through one paragraph of explanatory writing, one piece of evidence per row, from the lead-in that prepares the reader through the explanation that makes the evidence do work. The habit it is built to break is the dropped quotation, in which a student pastes a source's sentence into a paragraph and moves on as though the sentence explains itself. The water content carries its own misconception, and it is worth naming while students fill the frame: students commonly assume that a running pump is what makes water come out of a tap with force, when in a gravity system the height of water in the tank sets the pressure and the pump only refills the tank.
Organizer
Your point. In the upper pressure zone of the town of Shelvock, the height of the water in the Tarn Hill tank, rather than the pump, is what holds pressure steady at a customer's tap.
Source notes. Every number below belongs to this invented scenario except the constant in Note 4.
- Note 1. Shelvock's upper zone sits about 140 feet higher than the treatment plant.
- Note 2. The district's standard is to hold between 45 and 65 psi at every service connection in the zone.
- Note 3. Two booster pumps lift water from the plant up to the Tarn Hill tank. One runs while the other rests.
- Note 4. A column of water 2.31 feet tall produces one psi of pressure at its base.
- Note 5. When the tank level drops to a set mark, the resting pump starts and refills it.
- Note 6. During the power outage on July 2, the tank held the zone within the standard for about seven hours with no pump running.
Directions. Fill one row for each piece of evidence you use. Work left to right across a row before starting the next row.
| Row | Lead-in: what the reader needs before the evidence | Evidence: quoted or paraphrased, with the note number | Explanation: how this supports the point | Link: the idea this hands to the next row |
|---|---|---|---|---|
| 1 | (write here) | (write here) | (write here) | (write here) |
| 2 | (write here) | (write here) | (write here) | (write here) |
| 3 | (write here) | (write here) | (write here) | (write here) |
| 4 | (write here) | (write here) | (write here) | (write here) |
Last step. Copy your four rows into one paragraph, reading left to right and top to bottom. Add nothing new. If the paragraph does not hold together, the missing piece is in a Link cell.
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Completed Exemplar
| Row | Lead-in: what the reader needs before the evidence | Evidence: quoted or paraphrased, with the note number | Explanation: how this supports the point | Link: the idea this hands to the next row |
|---|---|---|---|---|
| 1 | Shelvock's upper zone does not sit at the same height as the plant that treats its water. | The zone sits about 140 feet higher than the treatment plant (Note 1). | Water will not climb that difference on its own, so the town needs a way to get it up there and a way to hold it there. | Something has to lift the water first. |
| 2 | The district uses pumps for the lifting, and it uses two of them. | Two booster pumps carry water from the plant up to the Tarn Hill tank, and one rests while the other runs (Note 3). | The pumps move water into storage rather than pushing it out to customers, so a pump's job ends once the tank is full. | Once the water is in the tank, something else takes over. |
| 3 | Height itself creates pressure, and the amount is fixed. | A column of water 2.31 feet tall produces one psi at its base (Note 4). | Because the tank stands above the neighborhood, the water in it presses down through the pipes and produces the pressure a customer feels at the tap. | If the tank is what supplies the pressure, the pumps should be able to stop without the pressure stopping. |
| 4 | The town found that out during an outage it did not plan. | On July 2 the power failed, and the tank held the zone within the district's standard for about seven hours with no pump running (Note 6). | Pressure stayed within the standard while every pump sat idle, which shows the tank, not the pump, was holding it. | The paragraph's point is now supported by a case in which the pumps were removed from the picture. |
Model paragraph built from the rows. Shelvock's upper zone does not sit at the same height as the plant that treats its water, since the zone stands about 140 feet higher. Water will not climb that difference on its own, so two booster pumps carry it from the plant up to the Tarn Hill tank, one resting while the other runs. Those pumps move water into storage rather than pushing it out to customers. Height itself then creates the pressure, because a column of water 2.31 feet tall produces one psi at its base, and the tank standing above the neighborhood presses water down through the pipes. Shelvock saw the proof during the July 2 power failure, when the tank held the zone within the district's standard for about seven hours with no pump running at all.
Differentiation
Support
Fill the Lead-in column for all four rows in advance and let students complete only the Evidence, Explanation, and Link cells, so the writing load falls on the reasoning. Give these students only the four notes the exemplar uses (Notes 1, 3, 4, and 6) rather than all six, so that the paragraph still holds together, and complete row 1 together as a class.
Extension
Have students rebuild the paragraph in the opposite order, opening with the outage in Note 6 and working back to the height difference in Note 1, then write a short comparison naming which version a reader who knows nothing about water systems would follow more easily.
ELL supports
Provide a strip of lead-in openers such as "Before the water reaches," "The district measured," and "During the outage," and a matching strip of link openers such as "That raises the question of" and "Once the tank is full." Allow students to write the Evidence column as a paraphrase in short phrases rather than full sentences, and let them talk each row through with a partner before writing.
Extensions
Ask students to add a fifth row using Note 2 or Note 5 and to explain in one sentence why the paragraph works without that row, which is the judgment a writer makes when a true detail does not serve the point being made.