Scientificmethod 120724142851-phpapp01

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Scientificmethod 120724142851-phpapp01

  1. 1. •Experimental Design Research – The manipulation and control of variables • You absolutely, positively have to know what the variables are! 1. What you are changing? • How you are changing it? 2. What you are measuring? • How you are measuring? 3. Repeated trials 4. Data tables
  2. 2. So an experimental question has to indicate the variables: 1. How the independent variable will AFFECT the dependent variable 2. What the EFFECT of the independent variable will be on the dependent variable
  3. 3. For example… •How does the temperature of ocean water affect the speed of a hurricane? Independent variable is the temperature of ocean water. Dependent variable is the speed of a hurricane.
  4. 4. • Descriptive Design Research - Based mainly on observations. Ex. 1. Making models 2. Dissections 3. Observing animals in the wild Specific Example: How do the survivors of a disaster react to the disaster? No variables; data is based on watching and talking to survivors
  5. 5. •Good questions come from careful observations. •Questions beginning with what, why, how and when are very important in focusing on an investigation.
  6. 6. •An observation is any use of the senses to gather information. •Observations may be direct or indirect.
  7. 7. •Direct observations are made using one of your senses such as sight or touch. •Indirect observations are made by using an instrument such as a thermometer or a microscope.
  8. 8. •Observations usually lead to inferences. •An inference is a logical interpretation based on observations or prior knowledge (schema).
  9. 9. •Example of an observation: Shadows can change in length. •Example of an inference: The length of an object’s shadow depends on how near the object is to the light source.
  10. 10. •Determine if the following examples are observations or inferences. •You do not have to write these in your notes.
  11. 11. I turn on a fan. The blades of the fan are turning.
  12. 12. There is a whirring sound.
  13. 13. You feel a breeze.
  14. 14. The fan is pushing the air around in the room.
  15. 15. •A hypothesis is a clear statement of what you EXPECT the answer to your question to be. •Your hypothesis will represent your best “educated guess” based on what you have observed and what you already know (schema). •A hypothesis must be stated in an if- then format.
  16. 16. A hypothesis is a special kind of prediction. o What makes it so special??? • It’s a guess about the VARIABLES& their relationship, in particular, •How will the independent variable affect the dependent variable?
  17. 17. Here is an example of a hypothesis: If the researcher uses acid rain to water plants, then the plants’ growth will be slower.
  18. 18. Do NOT use personal pronouns!! Ithink that acid rain causes plants to grow more slowly.
  19. 19. •Hypothesis − a statement that uses a few observations − an idea based on observations without experimental evidence •Theory − uses many observations and has lots of experimental evidence − can be applied to unrelated facts and new relationships − flexible enough to be modified if new data/evidence is introduced •Law − stands the test of time, often without change − experimentally confirmed over and over − can create true predictions for different situations − has uniformity and is universal
  20. 20. • You test your hypothesis by doing an experiment. • Make sure you are doing an experiment and not a demonstration!
  21. 21. •Though modeling a volcano’s eruption is an interesting demonstration, it is NOT an experiment. •Experiment vs. Demonstration •Figuring out how altitude affects the boiling point of water is an experiment.
  22. 22. A controlled experiment tests only ONE factor. • A controlled experiment has a control group and one or more experimental group. • The control group and the experimental groups are EXACTLY the same except for ONE factor.
  23. 23. • The factor that differs is called the variable. • Because the variable is the only factor that differs, scientists know that this factor is responsible for the results of the experiment.
  24. 24. •An independent variableis what the scientist changes in the experiment. •A dependent variableis what changes in the experiment as a result of what the scientist does.
  25. 25. •While doing the experiment, be sure to write down all of the observations that you make. •Include any type of measurement using the metric system. •EX: time, date, height, size, amount, temperature, etc.
  26. 26. •Be as exact as possible in taking measurements. •Measure something more than once and use the average of the results.
  27. 27. Test More than One Subject! • Sample size is the number of subjects you test. •Your sample size must be large enough to allow you to draw accurate conclusions from your data.
  28. 28. •Do Multiple Trials! •When doing an experiment, perform each test several times.
  29. 29. After you have collected your data, determine what it means.
  30. 30. Tables and graphs are often useful in helping to organize the data. Distance Rolled for a Metal Sphere
  31. 31. All graphs should include: •Title •Label the axis •Include a key (legend) •Use distinct colors
  32. 32. •Every graph always needs a key so people can easily tell what each color or pattern represents.
  33. 33. 0 10 20 30 40 50 60 70 80 90 Week 1 Week 2 Week 3 Full Light Light deprived Tomato Plant Height
  34. 34. In a line graph, place the dependent variable on the vertical axis and the independent variable on the horizontal axis.
  35. 35. 0 10 20 30 40 50 60 1 2 3 4 Sample 1 Sample 2 Sample 3 Temperature Variation over 4 Hours
  36. 36. •Showing percentages is easy to do with a pie chart. •You can quickly see which group has the biggest slice and therefore contains the most data.
  37. 37. People who sneezed 43% People who didn't sneeze 57% Sneezing After Exposure to 10 Minutes of Bright Light
  38. 38. •Based on the analysis of your data, you should conclude whether your results reject or support your hypothesis. •If the data does reject or support the hypothesis, why do you think it does?
  39. 39. •REMEMBER that it is NOT important for the hypothesis to be correct. •What is important is that you explain WHY you got the results you did. •Be sure to mention in your conclusion what factors you believe contributed to your results.
  40. 40. •Briefly explain possibilities for new experiments that would control these factors. •Also, mention any investigative questions that came up during the experiment.
  41. 41. •Report your results by doing a written report. •Let others know what you have learned. •Once again, DO NOT use personal pronouns!!
  42. 42. • Be sure to include a bibliography, and no, Wikipedia is NEVER an acceptable source for any project throughout the entire year! • Give credit to the people who helped you in your project- your teacher, your parents, professional scientist, or others.

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