Write an explanation with a thesis that presents information, an organizing strategy, headings, a table and domain-specific vocabulary

Learning goal: Write informative/explanatory texts to examine a topic and convey ideas, concepts and information through the selection, organization and analysis of relevant content. Establish a thesis statement to present information; introduce the topic clearly, previewing what is to follow; organize ideas, concepts and information using strategies such as definition, classification, comparison/contrast and cause/effect; include formatting such as headings, graphics such as charts and tables, and multimedia to aid comprehension if needed; develop the topic with relevant facts, definitions, concrete details, quotations or other information and examples; use appropriate transitions to create cohesion and clarify the relationships among ideas and concepts; use precise language and domain-specific vocabulary; establish and maintain a formal style; and provide a concluding statement or section that follows from and supports the information or explanation presented.

Explaining is not arguing. An argument asks the reader to agree with a disputable claim. An explanation asks the reader to understand something: how a process works, what a term means, why an event happens, how two things differ. The same Fernbrook scenario from the argument lesson supplies the topic here, but the task has changed. The field committee has asked for a short report that explains, without recommending, why the lower field floods and how each proposal would change that. A reader of the report should finish knowing more, not persuaded of anything.

A thesis statement presents the information. In an explanation the thesis does not take a side; it states the main idea the text will convey and, ideally, how it will be organized. "This report is about flooding" announces a topic without an idea. "The lower field floods because water from paved surfaces reaches Miller Run faster than the ground can absorb it, and the two proposals differ in whether they speed that water up or slow it down" is a thesis that presents information: it names the cause, names the contrast and tells the reader what the sections will do.

Introduce the topic clearly and preview what follows; organize with a strategy. The introduction names the topic, says why it matters to this reader and previews the sections. Then the writer chooses an organizing strategy, and grade 7 asks you to know four by name. Definition explains what a thing is and what conditions make it that thing. Classification sorts things into groups by a rule. Comparison/contrast sets two things side by side on the same points. Cause/effect traces how one thing leads to another. A good explanation usually uses more than one, in a deliberate order: the model below defines its terms, classifies surfaces into two groups, traces a cause-and-effect chain and then compares the two proposals. Formatting such as headings makes that order visible, and a graphic such as a table lets the reader compare numbers in a way prose cannot. Multimedia (a short video of a rain garden filling, a photograph of the flooded field) may be included if it aids comprehension; if it merely decorates, leave it out.

Develop the topic with relevant facts, definitions, concrete details, quotations and examples. Development is the content itself. A fact is a checkable statement ("the field closed nine days last year"). A definition fixes a term. A concrete detail makes a general statement specific ("the bus loop is paved, about 900 square meters, and slopes toward the creek"). A quotation brings in a source's exact words when the wording matters ("the soil and water office letter describes a rain garden as 'a shallow planted basin that holds runoff for a day or two while it soaks into the soil'"). An example shows a general idea in one case. Relevance is the test for all of them: a detail about the creek's fish would be true and would not explain the flooding.

Use appropriate transitions to create cohesion. In an explanation, transitions tell the reader what kind of relationship is coming: first and next for sequence, because and as a result for cause and effect, in contrast and similarly for comparison, for example for an example, in other words for a restatement. Use the transition that matches the relationship. "As a result" in front of a definition misleads the reader as surely as a wrong road sign.

Use precise language and domain-specific vocabulary. Precise language chooses the word that says exactly what is meant: runoff, not the water stuff; impervious, not hard; establish, not grow in. Domain-specific vocabulary is the set of terms the field uses, and an explanation teaches them as it uses them, with a definition on first use. A writer who uses infiltration three times without defining it has not explained anything.

Establish and maintain a formal style; provide a conclusion that follows. The formal style of an explanation is plain, precise and impersonal: no "I think," no slang, no jokes at the topic's expense. The conclusion follows from and supports the information presented: it restates the main idea in light of the explanation and may point to what the reader can now do with it. It does not slip into a recommendation the report was not asked to give.

Original model explanation — Why the Lower Field Floods, and How Two Proposals Would Change It

Introduction. The lower field at Fernbrook Middle School closed nine days last year because of standing water, costing 27 physical education periods. The field floods because water from paved surfaces reaches Miller Run faster than the ground can absorb it, and the two proposals before the committee differ in whether they speed that water up or slow it down. This report explains that cause and describes how each proposal would change it. It defines the key terms, classifies the surfaces that drain toward Miller Run, traces the chain of causes and compares the proposals on the same four points. It does not recommend either proposal.

Key terms. Runoff is rainwater that flows across the ground surface instead of soaking in. Infiltration is the soaking-in of water into soil. An impervious surface, such as asphalt or a roof, lets almost no water infiltrate, so nearly all the rain that lands on it becomes runoff. A rain garden, in the words of the county soil and water office letter, is "a shallow planted basin that holds runoff for a day or two while it soaks into the soil." A planted bank, sometimes called a buffer, is a strip of trees and shrubs along a creek whose roots hold the soil and whose stems slow water crossing it.

Two kinds of surface. The ground that drains toward the lower field falls into two classes. Pervious surfaces, meaning the upper lawn, the wooded slope and the field itself, absorb some of the rain that falls on them. Impervious surfaces, meaning the bus loop, the west parking area and the gym roof, absorb almost none. The facilities memo estimates the bus loop alone at about 900 square meters, and it slopes toward the creek.

How the flooding happens. The chain has four links. First, rain falls on the paved bus loop and roof, and because those surfaces are impervious, nearly all of it becomes runoff at once. Next, that runoff reaches Miller Run within minutes, so the creek rises quickly. As a result, the creek spills over its low bank onto the field, which is the lowest ground on the property. Finally, the field's soil, already soaked by the same storm, cannot infiltrate the extra water, so it stands until it evaporates or slowly drains, which last year took long enough to close the field for nine days in total.

Comparing the proposals. The two proposals differ in a single principle. The drain and pipe speeds water up: once the creek has dropped back below its bank, the drain collects the water standing on and under the field and carries it into the creek faster than the ground would release it. It does not stop the creek from rising, and it can empty the field only while the creek is lower than the pipe's outlet, a detail the simulated memo does not give. The planting proposal slows water down: the rain garden holds runoff from the bus loop for a day or two while it infiltrates, and the planted bank slows water crossing it and holds the soil. Table 1 sets the two side by side.

Table 1. The two proposals on four points (all figures from the simulated facilities memo and soil and water office letter).

Conclusion. The field floods because impervious surfaces send rain to Miller Run faster than the ground can absorb it. The drain removes water from the field by moving it into the creek more quickly; the planting proposal reduces how much water arrives at once. The committee's choice is between speed of effect and where the water goes, and this report has set out the information on which that choice depends.

Reading the model. The thesis states the cause and the contrast. Each of the four middle headings names an organizing strategy at work: definition, classification, cause/effect, comparison/contrast. Transitions (first, next, as a result, finally, in contrast implied by the table) match the relationships they introduce. Domain-specific vocabulary is defined on first use and then used without apology. The table holds the numbers so the prose does not have to repeat them. The conclusion follows from the explanation and refuses the temptation to recommend. Every number is invented for this lesson.

Worked thesis for information: Draft: "This report is about the lower field and flooding and the two ideas." It names topics and presents no information. Revision: "The lower field floods because water from paved surfaces reaches Miller Run faster than the ground can absorb it, and the two proposals differ in whether they speed that water up or slow it down." The revised thesis presents the cause, presents the contrast and tells the reader that the report will explain a chain of causes and then compare. A reader could summarize the whole report from it.

Worked organizing strategy, chosen and signaled: A student wanted to explain the flooding but wrote one long paragraph mixing definitions, causes and the drain's cost. Choosing strategies fixed it: a definition section for runoff, infiltration and impervious; a classification section sorting surfaces into pervious and impervious; a cause/effect section with four links marked first, next, as a result and finally; and a comparison/contrast section with a table. Headings named each section so a reader could go straight to the part needed. The content did not change; its organization did, and the explanation became readable.

Worked development with a relevant fact and a concrete detail: General sentence: "Paved areas cause a lot of runoff." To develop it: a fact ("the bus loop is impervious"), a concrete detail ("about 900 square meters, sloping toward the creek") and an example ("in a storm of 10 millimeters, that loop sheds roughly 900 times 0.010, or 9 cubic meters, which is 9,000 liters"). Check the arithmetic: 900 square meters times 0.010 meters is 9 cubic meters; one cubic meter is 1,000 liters; 9 times 1,000 is 9,000 liters. The developed version lets the reader picture the quantity; the general sentence did not.

Worked precision and formality edit: Draft: "Basically the water stuff runs off the hard parts super fast and the field gets soaked." Edit: "Runoff from the impervious surfaces reaches the creek within minutes, and the field, which is the lowest ground, floods." Runoff and impervious replace water stuff and hard parts; within minutes replaces super fast; basically is cut because it says nothing. The edit is three words longer (19 words against 16) and far more exact; precise language and a formal style are measured by what the words say, not by how few there are.

Organization record: Choose one part of the scenario to explain (how a rain garden works, why a pipe moves water faster, or how the field's closures affected physical education). Write a thesis that presents information. Then plan three sections, each labeled with the organizing strategy it uses (definition, classification, comparison/contrast, cause/effect) and given a heading. For each section list the facts, definitions, concrete details, quotations or examples you will use and the simulated source of each. Mark the transition you will use to open each section and say what relationship it signals. Decide whether a table, chart or piece of multimedia would aid comprehension; if so, sketch it and its title.

Independent performance: Write a 400-word explanatory report for the field committee on a topic from this scenario. Success criteria: a thesis statement that presents information, not a position; an introduction that names the topic and previews what follows; at least two named organizing strategies, each in its own section under a heading; at least one table or chart whose title says what its numbers are; development with relevant facts, at least two definitions on first use, one concrete detail and one quotation from a simulated source; transitions that match the relationships they introduce; domain-specific vocabulary used precisely; a formal style throughout; and a concluding section that follows from the explanation and makes no recommendation. Submit the plan, the draft and the final with the sections labeled by strategy.