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A claim is a statement that represents the most important information that the author wants you to learn about the topic or concept. Authors support their claims through evidence which may consist of facts, research findings or statistics, and quotes from experts. When considering the evidence, the reader must assess the clarity of the reasoning, which is how the writer explains the importance of the evidence and makes specific connections between the evidence and how it supports the claim. The better the reasoning, the stronger the author’s claim.

This is an illustration showing the process of reverse osmosis. An arrow labeled reverse osmosis points left from one side of a u-shaped pipe to the other. A nozzle labeled external pressure in shown pushing seawater down the pipe through a membrane. On the other side of the membrane, freshwater is shown and labeled as such.

Reverse osmosis uses a semipermeable membrane, which acts like an extremely fine filter to create drinking water from contaminated water or saltwater. Pressure is applied to the saltwater or contaminated water part of the filter, forcing only water molecules and the tiniest molecules through the membrane to the other side. The final result is cleaner water.

Read the following excerpt from the article “California to tackle water scarcity by converting seawater Opens a new window,” and then explore the slideshow to learn how to identify the author’s claim and assess the reasoning and evidence.

Thirsty State's Eager Anticipation

Reverse-osmosis desalination was invented in California in the 1950s, but since then it has mostly been used outside the United States. When the Carlsbad plant begins operating in 2016, it will be the largest desalination project ever built in the Americas.

The eyes of a thirsty state are on this project: It is an all-important test for an industry eager to expand in California, where residents are famously protective of their coastline and are accustomed to cheap water.

“This plant can’t come online fast enough,” said Bob Yamada, water resources manager at the San Diego County Water Authority, which serves 3.1 million people and is buying all of the plant’s freshwater production. “It’s drought-proof," he said. "It will be the most reliable water source we have.”

— Newsela Opens a new window, December 4, 2014


Bolded terms in the slideshow are defined in the Glossary.

Speaker plays audio

Identifying Claims and Evidence

A thought bubble appears above a student reading a text. The thought bubble reads: What is the author’s claim?

When writing about a scientific topic or concept, authors implicitly or explicitly reveal their claim. When authors are explicit, they directly state their claim about the topic. When authors are implicit, the reader must read carefully in order to infer the author’s claim by looking at the evidence.

a graphic organizer shows the words support the claim in a center circle and four boxes with arrows pointing to the center circle. The boxes are labeled facts, research findings, statistics and quotes from experts.

To support the claim, authors must present evidence such as:

  • Facts
  • Research findings from text and/or experiments
  • Statistics
  • Quotes from respected experts and/or scientists in the field
The words reasoned judgement appear above a student reading a text.

Authors must explain how the evidence supports their claim. Such an explanation is called reasoned judgment. The more logical the reasoning, the more likely the reader will be to accept the author’s claim.

The words supporting claims with evidence appear above an illustration of a balance scale with cons on one side and pros on the other side of the scale.

When authors support their claim with evidence, such support may come in the form of pros and cons that help the reader to gain a balanced and complete understanding of the topic or concept presented.

The words assessing evidence appear above a student reading a text.

When assessing evidence, the reader must think about the strengths and limitations of that evidence. Ask yourself:

  • What evidence supports the author’s claim?
  • Is the evidence from a reliable source and presented in a way that is not biased?
  • Does the author offer reasoned judgment to explain how all evidence relates to the claim.

Such assessments will aid the reader in knowing what further reading or learning is required.