Common Core LiteracyGrades 6–8Science & Technical

RST.6-8.8: Facts, Reasoned Judgment and Speculation

Also written as CCSS.ELA-LITERACY.RST.6-8.8 · Cluster: Integration of Knowledge and Ideas.

The Official Wording

Distinguish among facts, reasoned judgment based on research findings, and speculation 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.6-8.8 Means in Plain English

Students in grades 6 to 8 sort what a science text states as checked fact, what scientists concluded from their data, and what is only a guess. A date from radiocarbon tests is fact; a cause nobody has evidence for yet is speculation.

Fifth graders (RI.5.8) explained which reasons and evidence support which points. This strand, which begins in grade 6, asks whether a claim is supported at all, and by what. In ninth and tenth grade (RST.9-10.8) students judge whether a text’s reasoning and evidence support its claim.

RST.6-8.8 I Can Statements

I can tell a fact from a conclusion drawn from research.
I can spot the words that signal a guess.
I can explain what evidence backs a claim in a science text.

RST.6-8.8 Worked Example

The article moves from dated facts to a research conclusion to open guesses, and the weak answer treats all of it as fact.

Read the Story

Woolly mammoths disappeared from most of their range more than 10,000 years ago. A small herd survived on Wrangel Island, off the coast of Siberia, until about 4,000 years ago, centuries after the Great Pyramid of Giza was built.Those dates come from radiocarbon tests on mammoth bones, teeth and tusks found on the island.Researchers compared ancient DNA from the island mammoths with DNA from older mainland mammoths and found the island herd had lost much of its genetic variety. From that evidence, they concluded the herd began with eight or fewer animals and never grew past a few hundred.Perhaps a new disease or a string of brutal winters finished them off. No one knows yet.Some writers imagine that mammoth-like elephants, made with gene editing, could one day roam the Arctic again and help keep its frozen ground from thawing.

A short passage written for this page.

Question: Sort the claims in this article into facts, reasoned judgments based on research, and speculation. Which sentences belong in each group, and what words tell you?

Not Yet“Everything in the article is a fact, because it is a science article. Mammoths died out about 4,000 years ago, and they might come back.”It treats being printed in a science article as proof, lumps a dated fact together with a guess about the future, and never sorts a single sentence or points to a signal word.

Meets the Standard“Fact: mammoths lived on Wrangel Island until about 4,000 years ago, which radiocarbon tests on their remains show. Reasoned judgment: the herd ‘began with eight or fewer animals.’ Nobody counted them; researchers concluded it from the lost genetic variety in the DNA, and ‘from that evidence, they concluded’ signals it. Speculation: that a disease or brutal winters finished them off, and that gene-edited elephants ‘could one day’ roam the Arctic. ‘Perhaps,’ ‘no one knows yet’ and ‘imagine’ show that no evidence backs those yet.”It puts at least one claim in each group, explains what kind of support each one has, and names the signal words that mark the difference.

Question Stems to Use

Could someone check this with a measurement or a record?What research is this conclusion based on?Which words show the author is guessing?Is this claim about what happened or about what might happen?How sure should a reader be of this sentence, and why?

Common Mistakes with RST.6-8.8

Trusting everything printed in a science text

“It’s in the article, so it’s a fact.”

Try this: Ask “How could anyone know this?” about each claim and have students write the answer: a measurement, a study or nothing yet.

Calling a research conclusion an opinion

“The eight-mammoth part is just their opinion.”

Try this: Show that a reasoned judgment names its evidence, and have students underline the finding each conclusion in the text rests on.

Missing the hedge words

“Mammoths died from a disease.”

Try this: Have students circle words like perhaps, might, imagine and could one day, then reread each circled sentence as a guess.

Where RST.6-8.8 Fits

Comes BeforeRI.5.8Explain how an author uses reasons and evidence, and which evidence supports which point.

AlongsideRH.6-8.8Tell apart fact, opinion and reasoned judgment in a history or social studies text.RI.8.8Trace and evaluate an argument, judging whether its reasoning is sound and its evidence relevant and sufficient.

Comes NextRST.9-10.8Assess how well the reasoning and evidence in a science text support the author’s claim or recommendation.

Practice RST.6-8.8

Quick Check

How do scientists know when the last mammoths lived on Wrangel Island?
From radiocarbon tests on mammoth bones, teeth and tusks found on the island.
What conclusion did researchers draw from the ancient DNA, and why is it a reasoned judgment?
That the herd began with eight or fewer animals. Nobody saw it happen; they concluded it from the herd’s lost genetic variety.
Which claims in the article are speculation?
That a new disease or brutal winters finished the mammoths off, and that gene-edited elephants could one day roam the Arctic again.

RST.6-8.8: Other Names

RST.6-8.8CCSS.ELA-LITERACY.RST.6-8.8