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Claims, evidence and reasoning are the building blocks of a well-written explanation. When writing about a science topic or concept, writers are often faced with a challenging question or problem that they must address. The claim(s) in a text answers the question or makes a statement that addresses the problem. It is the writer’s responsibility to support a claim with evidence and reasoning so that the reader has a deeper understanding of the topic.

Explore the slideshow below to learn about how claims, evidence and reasoning are used in developing an explanation.

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Claims, Evidence and Reasoning

Chart displaying Written explanation with claims, evidence and reasoning bullet points below. Two hands are shown typing on a laptop computer

A written explanation is often made up of a claim, evidence and reasoning. Together, these three components help readers to better understand what you write.

image of a desalination plant; text beside image reads Claim: Desalination is expensive and uses a lot of energy.

A claim is a conclusion that answers a question about scientific phenomena or a solution to a problem.

For example, in this claim from the Newsela article about water scarcity, the writer states that desalination, a process for removing salt from ocean water, is expensive and uses a lot of energy.

To explain and support this idea, the writer must provide sufficient evidence.

flowchart with claim: desalination is expensive and uses a lot of energy in the top box and another box labeled evidence with an arrow pointing from evidence to the claim box at the top

Writers include evidence to support claims. Evidence can be presented with facts, data, examples, research findings and quotes from experts. Evidence must be sufficient and relevant to your claim.

same flowchart from previous slide; the Evidence box reads: ‘The water will cost $2,257 per acre-foot, about double the price of the authority’s most expensive supply now. (example); ‘One of the big challenges is energy demand.’ (research finding)

Examine the evidence that the writer uses to support this claim. The writer uses an example to show the high cost of desalination and a conclusion from research about how much energy might be required.

Same flowchart from previous slide. A box labeled reasoning is added with an arrow pointing from the evidence box to the reasoning box and an arrow pointing from the reasoning box to the claim box at the top.

However, evidence alone may not be enough to help the reader understand or accept your claim as a writer. A good explanation will include the reason why the evidence supports the claim. Reasoning should be logical and valid.

same flowchart from the previous slide with text in the reasoning box that reads: The amount of electricity needed drives up the cost of the water steeply.

Examine the reasoning that connects the evidence to the claim in this example. The writer explains that the amount of energy needed drives up the cost of the water.

student typing on a computer with documents and a highlighter on the table in front of him

As you write explanations on scientific topics, be sure to support your claims with sufficient evidence and logical reasoning that explains why your evidence supports your claim.

Now go the next page to practice identifying claims, evidence and reasoning in a text.