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THE SCIENTIFIC METHOD

THE SCIENTIFIC METHOD. I. Observations. An observation is a description of an object or event by using one of the 5 senses . It is 100% true statement; a fact. For example: The grass is wet. II. Inferences.

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THE SCIENTIFIC METHOD

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  1. THE SCIENTIFIC METHOD

  2. I. Observations • An observationis a description of an object or event by using one of the 5 senses. • It is 100% true statement; a fact. • For example: The grass is wet.

  3. II. Inferences • In science, making an inference is when a conclusion is drawn based on information that may not be complete. • You infer something based on factual data. • Example of Inferences: • 1. The grass is wet (factual information) because it rained (inference). • 2. The grass is wet (factual information) because the sprinkler was on (inference).

  4. IF, THEN, BECAUSE! III. Hypothesis • A hypothesisis an educated guess that can be tested to prove or disprove the hypothesis. • A hypothesis is a suggested answer to a problem WITHOUT the support of data. • A hypothesis is made BEFORE the experiment is performed. • A hypothesis is always written as:

  5. IF it rained outside, THEN the grass will still be wet, BECAUSE the sun didn’t dry off the water. • IF kids eat a lot of candy THEN they will get cavities BECAUSE sugar causes tooth decay. • Hypotheses are similar to cause and effect (much like ELA) but they also include a reason WHY

  6. IV. Putting it All Together: • Observation: The grass is wet. • Inference: The grass is wet because it rained outside. • Hypothesis:Ifit rained outside, then the grass will still be wet because the sun didn’t dry off the water.

  7. V. What is a theory? • A theoryis an explanation made with the support of data from an experiment. • A theory is based on complete information but is NOT a fact. 1. Big Bang Theory 2. Global Warming Theory 3. Pangaea Theory

  8. VI. Scientific Method • The scientific methodsare the ways in which scientists answer questions and solve problems. • There are 6 steps to the scientific method.

  9. VII. The 6 Steps of the Scientific Method 2 1 3 5 4 6

  10. The 6 Steps • Make an observation. a. Use your 5 senses! b. Not all senses have to be used at the same time. c. Example: Some plants are taller than other plants.

  11. The 6 Steps • 2) Ask a question. • Pose a question to try to figure out why you observed what you did. • Scientists often ask a question after making many observations. c. Example: Will fertilizers increase the growth rate of plants?

  12. The 6 Steps 3)Formulate Hypothesis, or write or develop a possible explanation for the problem. a. NOT a question, always a statement b. A hypothesis is a prediction, or an educated guess. c. Always written as: “IF…, THEN…, BECAUSE…” d. Example: If fertilizer is added to trees, then the plants will grow faster because the added nutrients will speed their growth.

  13. The 6 Steps 4) Test Hypothesis • Design a test that will support or disprove your hypothesis. • The test should be repeatable (you conduct the test more than once and get the same results every time).

  14. c. Controlled experiment: A part of your experiment that is not altered so that you can compare changes that occur in the experiment. i. Example-having 3 plants that are all the same type of plant. d. Variables are factors that CHANGE from group to group in an experiment. i. Example-changing the type of fertilizer that each plant gets.

  15. VIII. Control Groups • An experiment needs to be controlled because a scientist needs to determine that the thing they are testing for actually works. • A control is the standard to which everything is compared.

  16. IV. Experimental Groups • The experimental group is the group that tests the variables.

  17. b. Two types of variables: 1. Independent variable is: the variable you change in the experiment 2. Dependent variableis: the variable you are measuring c. Example: You want to measure the effect of the sun on plant growth. What do you change? What do you measure? Amount of sunlight Growth of the plant

  18. d. The effect of the INDEPENDENT VARIABLE (sun) on the DEPENDENT VARIABLE (growth of plants).

  19. e. Examples • The effect of sunlight (IV) on the growth of plants (DV). • The effect of cold medicine (IV) on the number of sneezes(DV). • The effect of bleach(IV)on the growth of bacteria(DV). Independent Variable (IV) Dependent Variable (DV)

  20. Group 1 Group 2 • 3 trees • All have same volume of water and same amount of sunlight • 3 trees • All have same volume of water, same amount of sunlight, and same amount of fertilizer What’s DIFFERENT? The fertilizer. The fertilizer is the VARIABLE.

  21. Group 1 Group 2 • 3 trees • All have same volume of water and same amount of sunlight • 3 trees • All have same volume of water, same amount of sunlight, and same amount of fertilizer Which is the CONTROL? A control is the basis for comparison. GROUP 1 is the control because to find out if the fertilizer worked, you need to compare it with something that doesn’t have fertilizer.

  22. Fertilizer is the VARIABLE (different). This is the control because it doesn’t have the VARIABLE (the fertilizer). This is the experimental group because it is why you are doing the experiment. Control Experimental • All have same volume of water, same amount of sunlight, and same amount of fertilizer • 3 trees • All have same volume of water and same amount of sunlight -Fertilizer is the INDEPENDENT VARIABLE -Growth is the DEPENDENT VARIABLE

  23. A beaker of liquid changes from blue to green overnight and a bottle of Windex is left in the room. HYPOTHESIS: IF the Windex mixes with the liquid, THEN the liquid will change green BECAUSE the chemicals in Windex react with the liquid TEST: Set up two beakers of the liquid in the same spot as the previous ones. Add Windex to one (A) and add nothing to the other (B). WHY? EXPERIMENTAL GROUP: Beaker A CONTROL GROUP: Beaker B INDEPENDENT VARIABLE: Windex DEPENDENT VARIABLE: change in color

  24. The 6 Steps 5) Analyze/Interpret the results. • After you have measured and recorded information, what do they mean? • Did the trees with the fertilizer (experiment group) grow more than those in the control group (without the fertilizer)?

  25. The 6 Steps • 6) Draw conclusions. • Look back at your hypothesis. • Does your data support your hypothesis or reject it?

  26. X. What makes a good experiment? • Same Size of all Groups i. Example: 50 people in control and 50 people in the experimental ii. WHY? More or less people can alter the results of the experiment.

  27. b.) Large Sample Size i. The large sample size reduces the possibility that the results are due to chance. c. Repeating the Experiment i. Every scientist from around the world should be able to repeat your experiment and obtain the exact same results.

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