Aim #3: How can we use the scientific method to understand the world around us? Textbook Pgs: I. What is the Scientific Method?

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1 Name: Date: Aim #3: How can we use the scientific method to understand the world around us? Textbook Pgs: 6-13 I. What is the Scientific Method? 1. The scientific method begins with Scientific Inquiry = The diverse ways in which scientists study the and propose based on the they gather 2. Scientific Method: an organized set of II. Scientific Method Example: Let s go back a few years Long ago, many people believed that living things could come from nonliving things. They thought that worms came from wood and that maggots came from decaying meat. This idea was called spontaneous generation. In 1668, an Italian biologist, Francesco Redi, did experiments to prove that maggots did not come from meat. Redi placed pieces of meat in several jars. He divided the jars into three groups: He left the first group uncovered with meat in it. He covered the second group of jars with a fine cloth so only air could get in. Conclusion: Redi observed the jars for several days. He saw flies on the cloth of the covered jars but no flies in the jar), and he saw flies laying eggs on the meat in the uncovered jars. Maggots appeared only on the meat in the group of jars left uncovered. 1. What was the problem in Redi s experiment? a. How do maggots appear in meats? b. How do worms appear in wood? c. Is spontaneous generation a valid explanation for maggots in meats? d. All of the above are examples of problems. 2. What do you think his hypothesis was? a. Maggots grow through spontaneous generation. b. Maggots come from eggs laid by flies. c. Maggots find their way into woods and meats. d. The problem cannot be solved. 3. How did he test his hypothesis? a. He placed food in two jars, covering one jar and leaving the other uncovered. b. He placed food in two jars and left both jars uncovered. c. He placed food in two jars and covered both jars. d. He put food in one jar and no food in a second jar. 4. What was the variable in his experiment? 5. What do you think Redi s conclusion was? a. Covering both jars. a. Living things come from other living things. b. Covering one jar and leaving the b. Living things are created through other uncovered. spontaneous generation c. Leaving both jars uncovered. c. He did not have enough data to make a d. There was no variable in this experiment. Conclusion

2 III. What are the steps to the Scientific Method? 1. Identify the 4. Test the 2. Gather 5. Collect 3. State a 6. State a

3 III. What are the components of a controlled experiment? Controlled Experiment: An experiment that tests the effects of Why is it important that we only test the effects of ONE VARIABLE? Answer Below 1. Variables: A factor that can in the results of an experiment. i. Independent Vs. Dependent Variable Independent Variable Dependent Variable A.K.A the variable. The variable that I The in your hypothesis Ex: If I add fertilizer to the soil, then plants will grow taller ID = A.K.A the variable. The variable that is The in your hypothesis Ex: If I add fertilizer to the soil, then plants will grow taller DV = ii. Controlled Variables (Constants) variables that need to so they don t affect the results Ex: Plants receive the same amount of water/soil, same plant type used, pot size is the same 2. Control Group and an Experimental Group Control Group Experimental Group Used for Under conditions Does not receive being tested Ex: 5 plants kept in the classroom with the same soil type and type of plant under normal light, water and temperature conditions as the experimental group. BUT they do NOT receive treatment = fertilizer Receives the variable that is being Ex: 5 plants kept in the classroom with the same soil type and type of plant under normal light, water and temperature conditions as the plants in the control group. BUT they receive treatment = fertilizer

4 CIRCLE THE EXPERIMENTAL CROUP SQUARE THE CONTROL GROUP. EXPLAIN WHY WHAT IS THE INDEPENDENT VARIABLE? DEPENDENT VARIABLE WHAT ARE THE CONTROLLED VARIABLES/CONSTANTS?

5 WHY IS THIS WRONG?

6 Practice Identifying the Variable: QUESTION INDEPENDENT VARIABLE DEPENDENT VARIABLE Mary wants to find out whether plants produce more leaves when grown in red, blue or green light Tom wonders whether the speed of his model train affects the amount of time it takes the train to stop Christine is studying the pressure in a closed container at different temperatures John is trying to determine whether basketball players have lower blood pressures than people who don t play basketball Janet is doing an experiment to see if the number of peanuts produced per plant changes when the amount of fertilizer given to plants is changed Teresa wants to see if different brands of yeast make her loaves of bread rise to different heights Read the following and answer the questions below: Many people who are in favor of alternative medicine claim that large doses of vitamin C introduced into a vein speed up the healing of surgical wounds. Describe an experiment to test this hypothesis. In your answer include: o The difference between the experimental group of subjects and the control group o Two conditions that must be kept constant in both groups o Data that should be collected o An example of experimental results that would support the hypothesis

7 IV. How do we organize and analyze data? Recording and analyzing data are very important steps. Logically organizing data allows us to formulate a conclusion and state whether or not our hypothesis was supported or rejected. 1. show relationships in our data. They also allow us to make predictions 2. organizes our data throughout the experiment. Graphs can be created using information from a data table V. What are characteristics of a good experiment? 1. Can be the same way and get the same results 2. Have a sample size and test subjects 3. Performed over a period of time 4. Only variable is tested while all other characteristics 5. Are and examined by other scientists to determine its accuracy 6. The hypothesis must be 7. It is and unbiased. Fact and opinion should not be mixed. Bias occurs when what the scientist expects changes how the results are viewed. 8. The experiment follows standards that are and