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Cause and Effect


Shallow men believe in luck, believe in circumstances. Strong men believe in cause and effect. By looking narrowly you shall see there was no luck in the matter; but it was all a problem in arithmetic, or an experiment in chemistry. The curve of the flight of the moth is preordained, and all things go by number, rule, and weight.

Ralph Waldo Emerson

   Often times, the patterns we see in the natural and man-made world show that one thing consistently happens before something else.  This could be just a coincidence, but we sometimes find evidence that supports that one thing happening causes another to happen. Volcanic eruptions are caused by a build-up of pressure in gasses beneath the surface of the earth.  Consistently eating foods high in cholesterol and sodium can lead to heart disease.  When I whistle, my dog comes running.  We call these cause and effect relationships.

   While cause and effect relationships are everywhere surrounding us, it is actually very difficult to "prove" that a cause and effect relationship exists.  For example, does my dog come because I am whistling, and knows this is the command to come?  Or does she just hear a noise and is going to investigate?  Or did she just walk into the room by chance, while I happen to be whistling.  In order to show that a cause and effect relationship exists, scientists need to collect lots of data. They need to show that one thing (the cause) consistently happens before the other thing (effect), and that the effect does not happen without the cause initiating it.  Analysis of the data will support whether a cause and effect relationship exists or not.  Often times scientists will create a hypothesis (prediction) about a cause and effect relationship and design an experiment to build the evidence they need to determine if that cause and effect relationship exists or not.


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Writing and Speaking about

Cause and Effect Relationships

Students often struggle with how to discuss cause and effect in their writing, or when speaking with their peers. 

Here are some sentence frames to help with the discussion:

  • What effect does __________________ have on ________________?

  • How does_____________ affect the patterns found when _________________?

  • How does ________________ cause a change in ________________?

  • Why is there a cause and effect relationship between ____________________  and ________________?

  • The evidence shows a cause and effect relationship.  As ________________ increases, __________________ also increases.

  • The evidence shows that as ___________________ increases, __________________ decreases.  This pattern shows that a cause and effect relationship exists.

  • There is a cause and effect relationship.  Whenever _______________ occurs, _______________ happens next.

  • The evidence does not show a clear pattern.  No cause and effect relationship exists.

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