Write an informative or explanatory text that narrates a historical event or explains a scientific procedure, with a thorough thesis, a cumulative organization, well-chosen development, precise language and a significant conclusion

Learning goal: Write informative/explanatory texts, including the narration of historical events, scientific procedures or experiments, or technical processes: establish a clear and thorough thesis to present and explain information; introduce a topic and organize complex ideas, concepts and information so that each new element builds on that which precedes it to create a unified whole, including formatting such as headings, graphics such as figures and tables, and multimedia when useful; develop the topic thoroughly with the most significant and relevant facts, extended definitions, concrete details, quotations or examples appropriate to the audience's knowledge; use varied transitions and sentence structures to link major sections, create cohesion and clarify relationships among complex ideas; use precise language, domain-specific vocabulary and techniques such as metaphor, simile and analogy to manage complexity, conveying a knowledgeable stance that responds to the discipline and the expertise of likely readers; and provide a conclusion that follows from and supports the explanation, for example by articulating implications or the significance of the topic.

Informative is not argumentative. An argument asks the reader to accept a claim that could be disputed. An informative or explanatory text aims to make the reader understand something: how a process works, what happened and in what order, what a concept means. It still has a thesis, but the thesis states what will be explained and the key idea that unifies it, not a position to defend. "The pendulum method measures g by turning a relationship between length and period into a straight-line graph" is an explanatory thesis. In history, the narration of events is explanatory when it tells what happened in order, with dates and causes as the sources establish them, and marks what is uncertain.

Building so that each element prepares the next. Complex information must be sequenced so that each new element builds on what precedes it. For a scientific procedure the logic is usually: what is being measured and why; the concept the method depends on; the equipment; the steps in order, each with its reason; how the raw data become a result; how to judge the result. A reader who meets "plot T² against L" before learning what T is has been asked to use a term not yet built. Headings mark the sections; a table can hold data that would clog a paragraph; a figure such as a graph shows a relationship at a glance. Multimedia, such as a short video of a correct release, is useful when motion or timing is hard to describe in words.

Developing the topic for the audience. The most significant and relevant facts are the ones the reader needs to understand the process, not everything you know. An extended definition goes beyond a one-line gloss: it states the term's meaning, what it includes and excludes, and gives an example and a non-example. Quotations, concrete details and examples should be matched to the audience's knowledge: a text for students new to physics defines period and oscillation; a text for a physics teacher does not.

Precise language and figurative techniques. Domain-specific vocabulary (amplitude, oscillation, slope, uncertainty) is precise; everyday substitutes ("how far it goes," "wiggle") are not. Metaphor, simile and analogy manage complexity when they map the unfamiliar onto the familiar, and they must be accurate in the respect that matters. Saying that a pendulum "is like a playground swing" is fair, because both are pivoted masses whose period depends on length; saying that "gravity pulls harder on heavy bobs so they swing faster" is a false analogy dressed as explanation.

A knowledgeable stance and style. Writers in science often use the passive or impersonal voice for procedures ("the bob was released"), which keeps attention on the method, though many journals now prefer the active voice, including "we"; follow the convention of the course or publication and keep it consistent. They state measurements with units and describe uncertainty. Historians narrate in the past tense, date events precisely and attribute interpretations. Matching these conventions signals a knowledgeable stance.

A complete model explanatory text (science).

Measuring Gravity with a Pendulum

What is measured. Near Earth's surface, a falling object gains speed at a nearly constant rate called the acceleration due to gravity, g, about 9.8 meters per second per second. A pendulum measures g without timing a fall, which is too fast to time accurately with a hand-held stopwatch; instead, it measures how long a swing takes. This text explains how the pendulum method turns the relationship between a pendulum's length and its period into a straight-line graph whose slope gives g.

The key idea: period. The period of a pendulum is the time for one complete oscillation: the bob moves from one side to the other and back to where it started, moving in the same direction. A single sweep from one side to the other is only half a period. For a small, dense bob on a light string, swinging through a small angle, the period T depends on only two things: the length L from the pivot to the center of the bob, and g. The relationship is T = 2π√(L/g). Like a metronome whose weight is slid higher to slow the beat, a longer pendulum swings more slowly.

The procedure. A stand is clamped to the bench, and the length is measured to the nearest millimeter. The bob is pulled aside no more than 10° and released without a push. After two swings, 20 oscillations are timed, so that the error in starting and stopping the watch is shared among 20 periods. Three trials are made at each of four lengths.

From data to a result. Squaring the relationship gives T² = (4π²/g)L. When T² is plotted against L, the points fall on a straight line whose slope equals 4π²/g. The table shows one set of hypothetical class results (T is shown to three decimal places; each T² is calculated from the unrounded period).

The slope between the first and last points is (3.623 − 1.209) ÷ 0.600 = 4.023 s²/m, so g = 39.478 ÷ 4.023 = 9.81 m/s².

Why it matters. The method shows how a careful procedure turns an everyday motion into a precise physical constant. Because the value of g varies slightly from place to place, from about 9.78 m/s² at the equator to about 9.83 m/s² at the poles, precise measurements of it are more than a classroom exercise.

A misconception. Students often think an informative text should contain every fact they found. Selection is the skill: a fact belongs only if the reader needs it to understand the topic.

Worked extended definition: Term: amplitude. Meaning: the greatest angle, or distance, the bob moves from its resting position. Includes: the angle at release when the bob is let go without a push. Excludes: the length of the string, and the full width of the swing from one side to the other, which is twice the amplitude. Example: released at 8° from vertical, amplitude 8°. Non-example: a bob swinging 16° from one extreme to the other has an amplitude of 8°, not 16°. Why it matters here: the formula T = 2π√(L/g) holds only for small amplitudes, which is why the procedure limits the release angle to 10°.

Worked narration of historical events (informative, history): Thesis: "In the autumn of 1893 the Lusk Glass Company cut its workforce in stages, as falling orders, a bank failure and a wage dispute unfolded over six months." Narrative: "Orders peaked at $22,100 in April and fell each month to $8,200 in September. On 3 August the company's bank suspended payment. On 15 August the company proposed a 15 percent cut in the wage list; the union refused, and on 1 September men who would not sign were locked out. On 30 September the second furnace was shut. Whether the company intended to end the union list is disputed by the sources." The narration is in chronological order, dated, uses transitions of time, and marks the disputed point without arguing it. (Benton Ferry and the company are invented for this unit.)

Worked transitions and sentence variety: Draft: "The bob is released. It swings. Then you time it. Then you do it again. Then you square it." Revised: "Once the bob has been released and has made two swings, 20 oscillations are timed. Because a single timing includes the observer's reaction error, three trials are made at each length. Only after all four lengths are complete are the periods squared and graphed." Changes: varied openings (a time clause, a causal clause, an inverted "Only after..."), impersonal voice, a common convention for a procedure, and transitions that show time and cause.

Plan and outline (representation): Choose a procedure, experiment, technical process or historical event from your coursework. Write a thesis that states what you will explain and the key idea that unifies it. Outline four to six sections with headings, arranged so each builds on the previous one. Mark where a table, figure or short video would help and describe it. Write one extended definition and one accurate analogy, noting in what respect the analogy holds.

Independent performance: Write an informative or explanatory text of 600 to 900 words. Success criteria: (1) a clear and thorough thesis that presents the information to be explained; (2) sections organized so each new element builds on the one before, with headings and at least one table or figure; (3) the most significant and relevant facts, one extended definition, concrete details and at least one quotation or example suited to a reader new to the topic; (4) varied transitions and sentence structures that clarify relationships between sections; (5) precise domain vocabulary and at least one accurate metaphor, simile or analogy; (6) the conventions of the discipline (units, stated uncertainty and one consistent voice for a procedure; past tense, dates and attribution for history); (7) a conclusion that states the implications or significance of the topic.