Dancing and running shake up the chemistry of happiness. Mason Cooley Mason Cooley Read more at GXGwY.99

Theories  Summarizes a hypothesis or group of hypotheses that have been supported with repeated testing by numerous individuals.  A theory is valid as long as there is no evidence to dispute it.  Theories can be disproven.  Explains how nature works

Laws  Generalize a body of observations.  At the time it is made, no exceptions have been found to a law.  Scientific laws explain things, but they do not describe them.  Law describes what nature does under certain conditions, and will predict what will happen as long as those conditions are met.  Scientific laws are similar to mathematical postulates. They don’t really need any complex external proofs; they are accepted at face value based upon the fact that they have always been observed to be true.

Telling Them Apart  One way to tell a law and a theory apart is to ask if the description gives you a means to explain 'why’  Laws are often times mathematically defined and can sometimes be expressed in terms of a single mathematical equation (once again, a description of how nature behaves)  Whereas theories are often non- mathematical.  The biggest difference between a law and a theory is that a theory is much more complex and dynamic. A law describes a single action, whereas a theory explains an entire group of related phenomena.

Example:  In fact, some laws, such as the law of gravity, can also be theories when taken more generally.  The law of gravity is expressed as a single mathematical expression and is presumed to be true all over the universe and all through time. Without such an assumption, we can do no science based on gravity's effects.  But from the law, we derived the theory of gravity which describes how gravity works, what causes it, and how it behaves. We also use that to develop another theory, Einstein's General Theory of Relativity, in which gravity plays a crucial role.  The basic law is intact, but the theory expands it to include various and complex situations involving space and time. Copyright © by Jerry Wilson

Technology  A branch of knowledge  Deals with:  The creation and use of technical means  Their interrelation with life, society, and the environment  Draws upon such subjects as:  Industrial arts  Engineering  Applied science  Pure science.

People in Technology  The people that have the most to do with technology are engineers that apply scientific information and principles to solve problems.  These solutions are technology.  The type of technology developed can be classified into groups based on the branch of science from which they grew.  Some examples of these are medical technology, nuclear technology and computer technology.

Chemicals  What is a chemical?  Anything you can put in a bottle or hold in your hand  Anything you can breathe or see or ingest or touch is made of chemicals.  Some things are single chemicals  pure water or oxygen  Others are mixtures of chemicals  shampoos  Anything made of atoms can be called a chemical.  Example:  Atoms are like individual Lego blocks. They are the smallest unit that anything can be broken down into without doing something crazy (like taking a blow torch to a Lego, or smashing atoms in a nuclear reactor).  So if atoms are Lego blocks, chemicals are the structures you can build with them.

Precision  Precision is how close the measured values are to each other.  Bias (don't let precision fool you!)  If you measure something several times and all values are close, they may all be wrong if there is a " Bias "  Bias is a systematic (built-in) error which makes all measurements wrong by a certain amount.  Examples of Bias  The scales read "1 kg" when there is nothing on them  You always measure your height wearing shoes with thick soles.  A stopwatch that takes half a second to stop when clicked Copyright © 2012 MathsIsFun.com

Accuracy  Accuracy is how close a measured value is to the actual (true) value.  Degree of Accuracy  Accuracy depends on the instrument you are measuring with.  But as a general rule: The degree of accuracy is half a unit each side of the unit of measure If your instrument measures in "1"s then any value between 6½ and 7½ is measured as "7" If your instrument measures in "2"s then any value between 7 and 9 is measured as "8" Examples: Copyright © 2012 MathsIsFun.com

Comparison Low Accuracy High Precision High Accuracy Low Precision High Accuracy High Precision Examples of Precision and Accuracy: So, if you are playing soccer and you always hit the left goal post instead of scoring, then you are not accurate, but you are precise! Copyright © 2012 MathsIsFun.com

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