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Scientific Explanations and Interpretations

Facts that come from observations or experiments lead to explanations.

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Science - Fact or Opinion?

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Do mermaids exist? Is skiing better than snowboarding?  What is the best food?

These questions may not be so easy to answer! 

Science is a way of thinking that helps people find evidence to support an answer.

This year we will learn about how science works - how evidence is collected and what science has to say about several topics.

This website has been edited and updated by me, chubbard, to serve as our text book.  So let's get started.



  • science: Knowledge about the natural world that is based on evidence that is gathered systematically.
  • observation: A bit of information that is collected by using the 5 senses, sometimes with the help of technology.
  • data: Facts/evidence that have been uncovered by systematic observations or experimental tests.
  • test: An intentional effort to collect observations that may help answer a question.

Basing ideas on facts is essential to science. Science is a way of collecting facts to explain the natural world.  There are many parts of life that are not part of science - opinion, poetry, art, and spiritual beliefs, for example.  But also topics for which we do not have ay evidence - like mermaids.  A real scientist would not tell you that mermaids do not exist.  Rather, she would say that no evidence has been found to support the existence of mermaids.

One of the most interesting parts of science is that new evidence is uncovered everyday, so science is constantly changing! Maybe one day we'll find evidence of mermaids.

Facts, Observations, Opinions

Scientists usually begin with a question, based on where the current evidence stops. A fact is a bit of information that is supported by evidence. This evidence, or data, is collected from observations or from experiments that have already been done. Data (singular: datum) are information that is not subject to opinion.  An opinion is simply what someone thinks or feels but is not based on evidence.  There is no such thing as an correct opinion. I like pizza, but you might prefer sushi.  Neither one of us can scientifically claim correct.

What is a fact? Look at the following list and identify if the statement is a fact (from observation or prior experiments), an opinion, or a combination.

Can you be sure from the photo that Susan has a cold?

  1. Susan has long hair.
  2. Susan is sneezing and has itchy eyes, so she must have a cold.
  3. Susan has two arms.
  4. Susan is beautiful.
  5. Susan is wearing a short sleeved shirt.

Remember - fact must have evidence to back it up.

An Analysis

The following is an analysis of the statements above:

  1. "Susan has long hair". This is a fact made from observation of the photo. Can you make it more factual?
  2. "Susan is sneezing and has itchy eyes, so she must have a cold". The is an inference, since she might actually have allergies or the flu. Susan might simply be blowing her nose.  Maybe she inhaled a bunch of black pepper. Maybe she is sad.  Can you turn this into a statement of fact?
  3. "Susan has two arms". Based on the evidence from the photo, this appears to be a statement of fact.
  4. "Susan is beautiful."  Maybe, maybe not.  This is an opinion and cannot be verified.
  5. "Susan is wearing a short sleeved shirt".  This is a fact based on evidence collected by looking at the photo.


  • Facts are based on evidence/data.
  • Some statements that appear to be facts are not. Some "facts" are actually inferences or opinions.
  • Some data come from observations of nature and some come from tests done on purpose to collect evidence.
  • All scientific explanations and interpretations are based on evidence.


1.  Explain the difference between a fact and an opinion.

2.  Please state one more fact about Susan, based on the photo.

3.  Now make an inference based on your new fact.

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