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Fair tests

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Fair tests

  1. 1. Fair Tests Types of Variables
  2. 2. Variables arethings that vary and change
  3. 3. VariablesIn any experiment there are 3 variables: An independent (changed) variable A dependent (measured) variable Some control variablesLet’s look at each type…
  4. 4. Independent Variable This is the thing you decide to changeeg. Investigating how plants grow when they are given different amounts of water You change the amount of water you give the plant. So, amount of water is the independent variable.
  5. 5. Dependent Variable This is the thing that changes as a result. This is the thing you measureeg. Investigating how plants grow when they are given different amounts of water You measure how much the plant grows. So, amount of growth is the dependent variable.
  6. 6. Control Variables These are all the things that must not change to make it a fair test. They must be kept the same. You need to keep the plants in the same place so that they get the same amount of sunlight or shade. You need to grow the plants in the same type of pot, that are the same size. The plants need to have the same type and same amount of potting mix. These are the control variables.
  7. 7. Summary The independent variable is changed.  Amount of water The dependent variable is measured.  Growth of plant. The control variables are kept the same.  Amount of sunlight or shade.  Type of pot.  Size of pot.  Type of potting mix, etc.
  8. 8. http://www.youtube.com/watch?v=Hxbz656Euyw
  9. 9. Change one thing, Measure one thing (usually),Keep everything else the same.
  10. 10. Time For A Joke... A Magician was driving down the  Q. What do u call a road... guy with no shins? then he turned into a drive way...  Tonyhahahahahahahahahah
  11. 11. Accuracy, Reliability and Validity
  12. 12. Accuracy The exactness or precision of a measurement; relating to the degree of precision in measurement. Highly dependant on equipment choice to measure values accurately
  13. 13. Reliability • The degree with which repeated observation and/or measurements taken under identical circumstances will give the same results.
  14. 14. Validity The extent to which the processes and resultant data measure what was intended. Are the measurements you recorded caused by the variables you think.
  15. 15. Reliability Have I tested with repetition? Have I chosen equipment that will giveAccuracy me accurate and precise readings? Does my experiment actually test the hypothesis that I want it to? WhatValidity variables have I identified and controlled?

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