1. The Scientific Method Part Two: Unit One, Lesson 2.2 By Margielene D. Judan2. LESSON OUTLINE Throwback: The Scientific Method Testing the Hypothesis Experimentation Three Types of Experiments Understanding Experimental Variables3. THROWBACK: THE SCIENTIFIC METHOD It is a systematic way of investigation in order to solve a problem.4. THROWBACK: BASIC STEPS OF THE SCIENTIFIC METHOD 1. State the problem or ask questions. (Observation) 2. Form a hypothesis. 3. Test your hypothesis by experimentation. 4. Record and analyze data. 5. State a conclusion. 6. Report your findings.5. The Scientific Method Flowchart (always use this chart when making scientific investigations)6. TESTING THE HYPOTHESIS To test the hypothesis, the experiment should be a fair test (you change only one variable at a time while keeping other conditions the same). To insure that your experiment is a fair test, you must change only one factor at a time while keeping all other conditions the same. Control group- the part of the experiment without the variables being tested Experimental group- the part that contains the variable being tested.7. EXPERIMENTATION Basically a test of hypothesis8. When experimenting, you must also make predictions. Predictions are forecasts of future events based on past observations.9. THREE TYPES OF EXPERIMENT 1. Controlled experiment 2. Natural experiment 3. Field experiment10. Controlled Experiments an experiment or trial that uses controls, usually separating the subjects into one or more control groups and experimental groups. A variable is a characteristic, number, or quantity that increases or decreases over time. It is anything that you can change or control in an experiment. There are three kinds of variables: (next slide)11. 3 Kinds of Variables Controlled variable- constant and unchanged in an experiment. Independent variable- factors which you change or alter during the experiment Dependent variable- response to an independent variable12. Natural or Quasi-Experiments No variable is being changed or altered Rely solely on observations to determine the factors which caused the phenomenon (ex. Astronomy. To prove that the earth is round, you dont need to change any variables. You cannot change the amount of sunlight, nor the shape of the earth. You just need to determine or identify the factors which caused the phenomenon.)13. Field Experiments applies the scientific method to experimentally examine an intervention in the real world rather than in the laboratory Often used in social sciences such as psychology, economics, and political science Field- outside the lab/not conducted inside a laboratory14. Example: (refer to your book p. 31) A group of student tested the effect of fertilizer on the growth of plants. They used six plants that are 15 cm tall. They grouped the plants into two groups: A and B. They watered the plants in group A with 200 mL of plain water and in group B with 200 mL of fertilizer solution. They watered the plants twice a week with the same amount of water and exposed them to the same amount of sunlight. After three weeks, they measured the growth of the plants in each group.15. Example: (refer to your book p. 31) Treatment: 200 mL of plain water twice a week for 3 weeks 18 cm tall 32 cm tall The following are the results: Group A Group B Treatment: 200 mL of fertilizer solution twice a week for 3 weeks16. Question 1: Which is the experimental and control group? Treatment: 200 mL of plain water twice a week for 3 weeks 18 cm tall 32 cm tall Group A Group B Treatment: 200 mL of fertilizer solution twice a week for 3 weeks17. Answer: Group A- control group Group B- experimental group Treatment: 200 mL of plain water twice a week for 3 weeks 18 cm tall 32 cm tall Group A Group B Treatment: 200 mL of fertilizer solution twice a week for 3 weeks18. Control group- the part of the experiment without the variables being tested (Group A has no variables tested. It is only watered with plain water. But a control group is important for us to be able to compare the results with the experimental group.) Experimental group- the part that contains the variable being tested. (Group B was watered with fertilizer [the variable being tested])19. Question 2: Which is the controlled, independent, and dependent variables? Treatment: 200 mL of plain water twice a week for 3 weeks 18 cm tall 32 cm tall Group A Group B Treatment: 200 mL of fertilizer solution twice a week for 3 weeks20. Answers: Controlled variable amount of sunlight, kind of plant, initial size of plant Independent variable -amount of fertilizer Dependent variable -growth of plant21. Answer: Controlled variable amount of sunlight, kind of plant, initial size of plant Controlled variable- constant and unchanged in an experiment. Both groups are have the same amount of sunlight, kind of plant, and have the same size at start of the experiment.22. Answer: Independent variable -amount of fertilizer Independent variable- factors which you change or alter during the experiment The difference between the experiment is that we used a fertilizer solution instead of water on group B.23. Answer: Dependent variable -growth of plant Dependent variable- response to an independent variable As a result to the fertilizer (independent variable), there is a difference in their growth size.24. Take note of these following terms. You need to be able to identify and differentiate each. They will always appear in our experiments and lab works. Experimental and control group Controlled, independent, and dependent variables A fair test25. Laboratory Tomorrow/next meeting (by group): Bring the following Three 250 ml transparent cups Cold, normal, and hot water Dropper Ink Two Stopwatches (1 is enough) Black, Blue, and Red Ballpen Ruler