Clear writing is not enough if the reader has no reason to believe it. A sentence can be perfectly crisp and perfectly false. This level is about how writers support what they say, how they bring other people's words and ideas into their own work, and why citation is a matter of honesty rather than fussiness. Judging whether a source is trustworthy in the first place is covered in MED 101; the focus here is on using sources well once you have them.

Claims and evidence

A claim is a statement a reader could reasonably doubt. Evidence is what gives them reason not to. Evidence comes in several kinds: statistics and other data, specific examples, documents, direct observation and the testimony of people with relevant expertise. Each kind has strengths. A well-chosen example makes an idea vivid; data show how widespread something is.

The key is to match the evidence to the size of the claim. A single vivid anecdote cannot prove a broad trend, because one case cannot show how common something is. A story about one student who thrived after a schedule change is a fine illustration, but a claim that the change helps most students needs evidence about most students. The reverse also holds: a table of averages may hide the human reality that one example would reveal. Strong writing often pairs the two.

Primary and secondary sources

A primary source is an original record or first-hand account: a letter, a diary, a court transcript, a dataset, a photograph, a law as it was passed, the original report of an experiment. A secondary source analyzes or interprets primary sources: a history book, a review article, a news analysis. Neither kind is automatically better. Primary sources let you see the evidence directly, while secondary sources supply context and expertise. When a secondary source summarizes a primary one, though, checking the original is a good habit, because summaries drift.

Quoting, paraphrasing and summarizing

Writers bring sources in three ways. A quotation reproduces the source's exact words inside quotation marks. A direct quotation is usually the best choice when the exact wording itself matters: the precise language of a law, a striking phrase, a statement whose tone is part of the point. A paraphrase restates a specific passage in your own words and sentence structure. A summary condenses a longer work to its main ideas.

Students sometimes think that rewording a passage makes it theirs. It does not. A paraphrase still needs a citation, because the idea still belongs to the source. And a quotation should never be dropped into a paragraph on its own. Introduce it with a signal phrase that names the source ("As the county's 2023 audit found..."), then explain what it shows and why it matters to your point.

Why cite?

Citation does three jobs. It gives credit to the people whose work you used. It lets readers check the evidence for themselves, which is much of what separates a supported claim from a rumor. And it shows where your work sits in a larger conversation. Common knowledge, such as the year a famous war ended or the capital of a country, generally needs no citation; specific statistics, contested claims and other people's ideas do.

Plagiarism is presenting another person's words or ideas as your own, whether by copying text, by paraphrasing too closely without credit or by passing off someone else's argument. It is dishonest toward both the original author and the reader, which is why schools, publishers and employers take it seriously.

Citation styles

Different fields use different formats, but all ask for the same basic information: who, what, where and when. MLA style, from the Modern Language Association, is common in literature and the humanities and puts the author's name and a page number in the text. APA style, from the American Psychological Association, is standard in psychology and many social sciences, and it puts the author and year in the text, because in fields where recent research matters most, readers want to see at a glance how current a source is. Chicago style, from the University of Chicago Press, is common in history and often uses footnotes; its manual first appeared in 1906. The details can always be looked up. Knowing why each style exists is what matters.

Worked example: school start times

A student writes: "Studies show schools start too early." This is a claim, but which studies? Too early for whom? A stronger version: "In 2014 the American Academy of Pediatrics recommended that middle and high schools start no earlier than 8:30 a.m., citing research on teenagers' sleep." This sentence names its source, states exactly what the source said and leaves the reader able to check it.

The student can then add an example, a quoted line from a local teacher, and a paraphrase of a study of a district that changed its schedule, each credited. Notice that the strengthened claim is also narrower than the original. It no longer says "studies show" something vague; it reports what one body recommended and why. Good evidence often forces a writer to say less, and to say it more accurately, which is a trade almost every reader is glad to accept.