The Scientific Method

Transcription

1 The Scientific Method

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3 The Question A Scientific Question can be answered by gathering scientific evidence (with measurements / observations) testable & measurable Do not use term better? How is that measured? An example of a scientific question is Which freezes faster fresh water or salt water?

4 RESEARCH Background Research Before you can begin your investigation, you must find out all the information you can that is known about your topic. Use textbooks and science books Science journals (usually high level) Internet resources -- (.edu or.gov) You must pay attention to the source Is the source bias? Is the source accurate?

5 The Hypothesis Developing a hypothesis - give possible outcomes for the tested variables. It is based on research & previous knowledge and observations. MUST be If Then. The If states what variables are being tested. The then part of the hypothesis must be collectable data. An example of a hypothesis is If fresh water and salt water are frozen, then the salt water will take longer to freeze.

6 Rationale Explain why the hypothesis is correct based on the review of the literature. Adding salt to water lowers the freezing point of water. This will cause salt water to take longer to freeze.

7 The Procedure (Experiment) The Experiment is a plan to test your hypothesis. It should be a detailed, step-by-step list of procedures and should describe the observations or measurements to be recorded. The control, dependent variable, independent variable, and constants need to be identified. An example of a procedure: 1. Label two, 500 ml containers with numbers 1 and 2 2. Fill the two 500 ml containers with 300 ml of fresh water 3. Add 10 g of salt in container # 1 4. Place the 2 containers in the freezer 5. Check the containers every 15 minutes and record your observations. 6. Record the time it took for the water to freeze. 7. Repeat steps 1-6 five times.

8 Variable(s) Variable: Any factor that can change in the experiment Independent Variable: A factor that is manipulated or changed (on purpose) Dependent Variable: Factor that is measured / observed / or recorded Control: The independent variable that is the normal condition Constants: variables that are kept the same for all groups

9 Let s Practice Variables List all variables that may affect our experiment, Which freezes faster fresh water or salt water?

10 Variables that may affect the experiment. Type of water Amount of water Temperature of water Type of salt Amount of salt Position in freezer Type and size of freezer Temperature of freezer Container used How close containers are to other objects How often the freezer door is opened

11 Let s Identify the following: Independent Variable Control Dependent Variable Constants Answers on next slide

12 Identify the following Independent Variable: Amount of salt (0% and 2.5% salt concentrations) Control: Freshwater (zero percent salt) Dependent Variable: Time it takes to freeze Constants: Type of water Amount of water Temperature of water Type of salt Position in freezer Type and size of freezer Temperature of freezer Container used How close containers are to other objects How often the freezer door is opened

13 DATA COLLECTION Data must be collected in a table. BEFORE experiment is done, you must have a data table. Use the header row of the table to list the units, do not list the units in each box. Time Elapses (min) Freshwater 0% Salt Saltwater 2.5% Salt

14 Interpreting Data Interpreting data means analyzing the information collected during the experiment looking for patterns or trends (relationships) This is best done by organizing your data into GRAPHS.

15 The Conclusion You need to state whether or not the data supports or does not support the hypothesis. Restate your data (use averages).

16 The Discussion Write about what you have learned from the experiment. - why did you get the results you did - evaluate your data - relate research to findings - real-life application of results - possible sources of error - ways to improve your project - ideas of further research

17 Let s Practice

18 Will house plants grow faster if you make the room warmer? 1. Variables that could affect the results: 2. Independent variable: 3. Dependent Variable: 4. Variables to be kept the same -- aka Constants 5. Control 6. Write a hypothesis. 7. Write a rationale.

19 Possible Answers: 1. Variables that could affect the results: Temperature, plants, soil type, amount of soil, containers, water, light, plant food 2. Independent variable: Temperature the plants are kept 3. Dependent Variable: Height of plant (growth) (You could also measure weight as an indicator of growth) 4. Variables to be kept the same: Constants Same kind of plant, same type and amount of soil, identical containers, same amount of water, same amount of light, same amount of food

20 5. Control: Room Temperature 6. Hypothesis: If house plants are grown in different room temperatures (15 o C, 25 o C, and 35 o C) then the plants grown in 35 o C will grow the fastest. 7. Rationale: The temperature affects the rate of chemical reactions. Because the rate of chemical reactions increases with temperature, the plant will grow faster in the higher temperature.

21 Answer for these two Questions: Question 1: Does fertilizer make a plant grow taller? Question 2: Is studying in a quiet place better than studying in a noisy place? 1. Variables that could affect the results: 2. Independent variable: 3. Dependent Variable: 4. Constants (variables to be kept the same) 5. Control 6. Write a hypothesis. 7. Write a rationale.

22 Does fertilizer make a plant grow taller? 1. Variables that could affect the results: 2. Independent variable: 3. Dependent Variable: 4. Constants (variables to be kept the same) 5. Control 6. Write a hypothesis. 7. Write a rationale.

23 Is studying in a quiet place better than studying in a noisy place? 1. Variables that could affect the results: 2. Independent variable: 3. Dependent Variable: 4. Constants (variables to be kept the same) 5. Control 6. Write a hypothesis. 7. Write a rationale.

24 Experiment 1 Helen thinks that a special juice will increase the productivity of workers. She creates two groups of 50 workers each and assigns each group the same task (in this case, they're supposed to staple a set of papers). Group A is given the special juice to drink while they work. Group B is not given the special juice. After an hour, The stacks of stapled papers is counted. Group A made 1,587 stacks, Group B made 2,113 stacks. Identify the: 1. Control Group: 2. Independent Variable: 3. Dependent Variable: 4. What should the conclusion be? 5. How could this experiment be improved?

25 Experiment 2 Bob notices that his shower is covered in a strange green slime. His friend tells him that coconut juice will get rid of the green slime. Bob decides to check this out by spraying half of the shower with coconut juice. He sprays the other half of the shower with water. After 3 days of "treatment" there is no change in the appearance of the green slime on either side of the shower. Identify the- 1. What was the initial observation? 2. Control Group: 3. Independent Variable: 4. Dependent Variable: 5. What should the conclusion be?

26 Experiment 3 Sam was told that a certain itching powder was the newest best thing on the market, it even claims to cause 50% longer lasting itches. Interested in this product, he buys the itching powder and compares it to his usual product. One test subject (A) is sprinkled with the original itching powder, and another test subject (B) was sprinkled with the Experimental itching powder. Subject A reported having itches for 30 minutes. Subject B reported to have itches for 45 minutes. Identify the- 1. Control Group: 2. Independent Variable: 3. Dependent Variable: 4. Does the data support the advertisements claims? 5. How could this experiment be improved?