Scientific Method

1. Scientific Method

2. The Way Science Works Over the past 300 years, people from all over the world have devised a verifiable, self-correcting system for answering “why” questions about nature. We call this systematic asking of questions and search for answers science. Science is, in essence, organized curiosity. Overtime, the systematic questioning, testing, and answering method came to be called the scientific method.

3. Scientific Method The scientific method consists of a set of steps used to investigate and solve problems in nature. • State the Problem • Gather Information • Form a Hypothesis • Test the Hypothesis • Analyze the Results • Draw a Conclusion

4. State the Problem The first step in solving any problem is to actually statethe problem. In the early part of the 20th century, the south’s cash crop – cotton – began to fail due to over farming. How can we increase the yield of cotton crops growing in nutrient poor soil?

5. Gather Information The second step in solving a problem is to gatherinformation.

6. Gather Information Born as a slave in 1865, George Washington Carver worked hard to earn a Masters degree in Agriculture before accepting a teaching position at The Tuskegee Institute in Birmingham, Alabama. Carver knew, from his studies, that legume plants, such as peanuts and soybeans, could replace the nitrogen in the soil that is removed due to over farming. Nitrogen Fixation

7. Form a Hypothesis The third step is to form a hypothesis which is a possible explanation that can be tested. Carver hypothesized that rotating cotton crops with nitrogen fixing crops, such as legume plants, would increase the yield of cotton.

8. Test the Hypothesis The fourth step is to test the hypothesis by performing an experiment. Carver and his students set up two fields. One on field, they continued to plant cotton. On the other field, they planted legumes for one year and cotton the next year.

9. Variables In an experiment, anything that can be changed, or can vary, is called a variable. • Amount of water • Amount of light • Size of field • Type of cotton seeds • Amount of cotton seeds • Planting technique • Crop rotation with legumes

10. Experimental Process Most scientific experiments contain two groups: an experimental group and a control group. In the experiment group, the variable that is being tested is changed. While in the control group, all the variables, including the one being tested, are left as natural as possible. Control Group Experimental Group No Crop Rotation Crop Rotation

11. Experimental Process After the experiment is conducted, the results of the experimental group can be compared with the results of the control group. Without the control group, you would not really know for sure if the results were due to what you changed or not. • Drought • Cold Spell • Bad seeds

12. Controlled Conditions Also, in order to be sure the results of an experiment are based only upon the variable being tested. All the other variables are kept the same, or constant. In other words, in a controlled experiment, only onevariable is tested at a time. • Amount of water • Amount of light • Size of field • Type of cotton seeds • Amount of cotton seeds • Planting technique • Crop rotation with legumes

13. Independent Variable The variable the person performing the experiment is actually changing, themselves, or is testing, is called the independentvariable. • Amount of water • Amount of light • Size of field • Type of cotton seeds • Amount of cotton seeds • Planting technique • Crop rotation with legumes

14. Dependent Variable The variable that is observed, measured, and recorded to see what effect the independent variable has on the experiment is called the dependentvariable. Amount of cotton produced

15. Analyze the Data The fifth step is to analyze the data or the information collected during an experiment.

16. Graphs Often, graphs are used to help visually show how data changed during the experiment. There are three types of graphs: Line Graphs Bar Graphs Circle Graphs

17. Line Graphs Linegraphs show the relationship between the independent and dependent variables over time. The dependent variable is always placed on the Yaxis and time is always on the X axis. Time (Days)

18. Bar Graphs Bargraphs are used for comparing quantities Cotton Yield Pounds of Cotton Cotton Crops

19. Circle Graphs Circlegraphs are used for showing percentages A Day in the Life of a Teenager Studying 10% School 30% Recreation 30% Sleeping 30%

20. Draw a Conclusion The sixth step is to draw a conclusion by deciding if the hypothesis was supported or not supported. Cotton Yield Rotating cotton crops with nitrogen fixing crops will increase the yield of cotton. Pounds of Cotton Hypothesis was supported. Cotton Crops

21. Hypothesis Not Supported If the hypothesis is not supported, then the hypothesis or the experiment can be modified. Or, the hypothesis may just be rejected. Unsupported hypotheses are still helpful because they tell us what doesn’t happen. “We have not failed, we have found over 1,000 ways how not to build a light bulb” Thomas Edison’s encouraging words to an assistant when they initially had no luck creating an efficient light bulb.

22. Hypothesis Supported If the hypothesis is supported and the experiment can be repeated, always producing the same results, then the hypothesis can be considered valid. Today, rotating crops with legume plants is common practice among organic farmers who don’t want to use commercial fertilizers. Peanuts Corn

23. Sharing Information Once a valid hypothesis is published and shared with the scientific community, other scientists can relate their own work to the experiment. Carver published pamphlets and brought a mobile school to farmers to share his findings and help poor farmers increase their crop yields.

24. Scientific Theory A hypothesis that is supported by many separate observations and experiments can become a scientifictheory. Legumes have a symbiotic relationship with nitrogen fixing bacteria that are able to convert atmospheric nitrogen into usable organic nitrogen.

25. Scientific Theory A scientific theory is an explanation of natural phenomenon that is supported by a large body of scientific evidence obtained from many different investigations and observations.

26. Scientific Law A scientificlaw or principle is a statement about what happens in the natural world which seems to be true all of the time. Laws do not explain how or why anything happens. The Law of Gravity states that the force of gravity is directly related to the sum of the masses between two objects and indirectly related to the distance between them. Does not explain what causes gravity

27. The End “Learn to do common things uncommonly well; we must always keep in mind that anything that helps fill the dinner pail is valuable.” George Washington Carver