Claims, Evidence,
and Reasoning
How to write a
scientific explanation
Claims
• Claims are statements that answer
your original question.
▫ The claim is usually one sentence in
length.
▫ It must be accurate, specific, and
completely answer the question.
Evidence
• The evidence is all of the scientific data
that supports your claim.
▫ Your evidence must be related to your
claim.
▫ Evidence can be specific data from a lab.
This can come from your own group or
another group in class.
Evidence (cont.)
▫ Evidence can also come from other sources
such as: computer simulations, websites,
textbook, class notes, personal experience,
etc.
▫ It is important to have numerous pieces of
evidence in order to prove your claim.
Reasoning
• Reasoning is the explanation that
connects your claim to the evidence
that supports it.
▫ Your reasoning shows why the data
you chose counts as evidence.
▫ This explanation acts as a
“conclusion” of your experiment.
Reasoning (cont.)
▫ It shows a detailed understanding of
the scientific principles involved and
uses correct science vocabulary.
▫ The reasoning should usually be at
least 2 to 3 sentences in length.
Real-World Claims
• People make claims all the time.
• Friends, parents and just about every
commercial on TV is making a claim about
something.
• Discuss some claims you have heard recently at
your table.
Some examples...
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Global Warming
Energy Drinks
Diets
Axe Body Spray
Airborne
Organic Food
Vaccinations
Sketchers
“2012”
Real-World Claims
What does Vince
want you to do?
Why is Vince so
convincing?
https://www.youtube.com/watch?v=Ns4mnmNBk1Y
We will watch the video again...
• Write down all the evidence that Vince uses to
convince you to buy Sham Wow.
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Holds 20x it’s weight in liquid
Demos – dried off the counter
Washable
Better for the environment
$20 a month on paper towels
Change the size
different/multiple uses
10 year warranty
Made in Germany – Germans make good
things?
What more could Vince do to convince
you that you should buy Sham Wow?
• Let’s make Vince’s presentation even better and
add the reasoning to his evidence.
Claim:
You should buy a Sham Wow.
Evidence:
Does not drip.
Holds 20 times it’s weight in liquid.
Absorbs all liquid from a carpet.
Reasoning: Next page
Reasoning:
The Sham Wow towel works so well because it contains
micro fibers. Micro fiber towels are made from two
synthetic (man made) materials, usually nylon and
polyester. The fibers are treated with chemicals and
mechanically changed to make them very small, smaller
that 1/100th the diameter of a human hair. This gives the
towel a lot of surface area to make contact with the spill
and absorb the liquid. The tiny fibers get into the small
places where most towel fibers cannot reach.
Source:
http://www.cleanlink.com/cp/article/Microfiber-101-The-Science-of-Tiny-Threads--3488
Claim, Evidence, Reasoning
• Claim, Evidence, Reasoning is a framework for
constructing scientific explanations.
▫ Claim – the main idea/what you know
▫ Evidence – the facts that support the claim
▫ Reasoning – explanation of the logic behind why
the facts support the claim
An explanation consists of:
A claim that answers the question.
Evidence from students' data.
Reasoning that involves a "rule" or
scientific principle that describes why the
evidence supports the claim.
Smile Video – ABC News report
about research into smiling.
• Look for the Claim, the Evidence, the
Reasoning.
• (Hint – ideas will not be presented in
that order)
You may take notes in
your science journal
http://abcnews.go.com/WNT/video/smiling-proven-make-us-happier-14822785
In your Science Journal:
• 1. What is the claim the reporter is making?
• 2. What evidence does she cite in the report that
supports that claim?
• 3. What is the scientific explanation (reasoning)?
▫ Physiological reason smiling makes you happy.
▫ Physiological reason people who smile feel
better.
https://www.youtube.com/watch?v=WQTsue0lKBk
1. Identify the Claim
2. Identify the Evidence
3. Identify the Reasoning – what
scientific explanation connects the
evidence to the little girl’s claim?