Common Core LiteracyGrades 6–8Science & Technical

RST.6-8.6: Author’s Purpose in Science Writing

Also written as CCSS.ELA-LITERACY.RST.6-8.6 · Cluster: Craft and Structure.

The Official Wording

Analyze the author's purpose in providing an explanation, describing a procedure, or discussing an experiment in a text.

Common Core State Standards, Grades 6-8, Reading: Science & Technical Subjects · Read it at the source · Checked October 14, 2026

What RST.6-8.6 Means in Plain English

Students in grades 6 to 8 explain why a science writer explains a concept, lays out a procedure or walks through an experiment. A writer describing Redi’s jars of meat step by step is showing how a fair test works, not just reporting where maggots come from.

Fifth graders (RI.5.6) compared accounts of one topic and the point of view each represented. This strand, which begins in grade 6, asks what each part of a science text is for. In ninth and tenth grade (RST.9-10.6) students also define the question the author seeks to answer.

RST.6-8.6 I Can Statements

I can tell whether a passage explains, gives steps or discusses an experiment.
I can explain why the author included that part.
I can name the question an experiment in a text answers.

RST.6-8.6 Worked Example

The author could have given the answer in one line, and the weak answer never asks why the experiment gets three paragraphs instead.

Read the Story

For centuries, people believed that living things could arise from nonliving matter. Rotting meat seemed to turn into maggots, so it was natural to think the meat made them. The idea was called spontaneous generation.In 1668 the Italian physician Francesco Redi tested it. He put pieces of meat in several jars. He left some open, sealed some tightly, and covered others with fine gauze, which let air in but kept flies out.Maggots appeared on the meat in the open jars, where flies had landed. None appeared on the meat in the sealed jars. In the gauze-covered jars, flies laid eggs on the gauze, and maggots hatched there, but not on the meat.The gauze jars mattered most. Critics had argued that sealing a jar kept out the fresh air life needed. Air reached the gauze-covered meat, and still no maggots grew on it.Redi did not end the debate about microscopic life, which went on for nearly two more centuries, but he showed how a fair test can overturn an idea that seems obvious.

A short passage written for this page.

Question: Why does the author describe Redi’s experiment in such detail, including all three kinds of jars, instead of just saying that maggots hatch from fly eggs?

Not Yet“The author wants to teach us about maggots and flies. Redi was a scientist from Italy.”It names the topic and a fact but not the purpose. It never asks why the experiment is told jar by jar or why the gauze jars get a paragraph of their own.

Meets the Standard“The purpose is to show how an experiment can disprove an idea, not just to give the answer. Describing all three jars lets the reader follow the logic: open jars got maggots and sealed jars got none, so the flies mattered. The author then singles out the gauze jars to answer the critics who said sealing kept out air. Air reached that meat and still no maggots grew on it. The last sentence states the purpose outright: a fair test can overturn an idea that seems obvious.”It states a purpose that fits the whole text, explains what each part of the experiment description does for that purpose, and uses the final sentence to confirm it.

Question Stems to Use

Is the author explaining, describing a procedure or discussing an experiment here?What would the reader miss if this part were cut?Why does the author give the steps instead of just the result?Which sentence tells you most directly what the author wants you to understand?What question was this experiment designed to answer?

Common Mistakes with RST.6-8.6

Naming the topic as the purpose

“The author wants to teach us about maggots.”

Try this: Have students complete “The author describes this so that the reader…” and reject any ending that only names the topic.

Answering “to inform” every time

“The purpose is to inform.” written for every paragraph

Try this: Ban “to inform” on its own and ask what the reader should be able to do or understand after this part.

Missing why one detail is singled out

Treating the gauze jars as one more detail, not the answer to the critics

Try this: Point to any detail the author stresses, like “mattered most,” and ask what doubt or objection it is there to answer.

Where RST.6-8.6 Fits

Comes BeforeRI.5.6Analyze several accounts of one event or topic and the point of view each represents.

AlongsideRI.8.6Determine an author’s purpose in nonfiction and how the author answers conflicting evidence or views.WHST.6-8.2Write explanations of procedures and experiments, choosing what to include for the reader.

Comes NextRST.9-10.6Analyze the author’s purpose in a science text and define the question the author seeks to address.

Practice RST.6-8.6

Quick Check

What was spontaneous generation?
The old belief that living things, like maggots, could arise from nonliving matter such as rotting meat.
Why did Redi cover some jars with gauze?
Gauze let air in but kept flies out, which answered critics who said sealed jars kept out the fresh air life needed.
What happened in the gauze-covered jars?
Flies laid eggs on the gauze and maggots hatched there, but none grew on the meat.

RST.6-8.6: Other Names

RST.6-8.6CCSS.ELA-LITERACY.RST.6-8.6