The Scientific Method

1. The Scientific Method

2. Scientific methodology is closely linked to exploration and discovery. Good scientists share scientific attitudes, or habits of mind, that lead them to exploration and discovery. New ideas are generated by curiosity, skepticism, open-mindedness, and creativity. Ideas for exploration can arise from practical problems.

3. Scientific Method- a precise method of investigation used by scientists that separates science from other ways of studying & learning

4. Scientific Method

5. Observations Scientific investigations usually begin with an observation, the act of noticing and describing events or processes in a careful, orderly way using the senses. For example, researchers observe that marsh grass grows taller in some places than others.

6. Stating the problem…. Observations can lead to questioning which is most often a statement of a problem: Why do marsh grasses grow to different heights in different places?

7. 5 Steps to the Scientific Method 1. State the problem.

8. Inferences After posing questions, researchers use further observations to make inferences, logical interpretations based on what is already known based on observation.

9. Inferences Researchers infer that something is limiting grass growth in locations throughout the marsh.

10. What’s wrong with Martha? Observation____________________ Inference__________________

11. Observation or Inference ?Students are working with a newly discovered organism. Is their statement an observation or an inference? ___ 1. The organism frowned to show it did not like strangers. ___ 2. The organism is green with pink spots. ___ 3. The organism moved away from us because it was scared. ___ 4. The organism made gurgling noises. ___ 5. The organism moves really slow so he must be old.

12. Before testing a hypothesis, it is useful to learn as much as possible about the background of the problem.

13. 2. Research/ Gather Information Research methods can vary depending upon the problem.

14. 3. Form a Hypothesis Hypothesis- a testable and clear explanation for observations; it can be supported or rejected by data; it is an educated guess often based on inferences Make it a definitive“if, then” statement

15. Forming a Hypothesis Based on their knowledge of marshes, the researchers may hypothesize that marsh grass growth is limited by available nitrogen. “If there is an increase in nitrogen in the soil, then grass will grow taller.”

16. Some hypotheses can only be tested simply by making observations, such as a study of wildlife. Controlling all the variables would therefore be difficult. Others can only be tested by building a model or simulator and relating it to real-life situations.

17. 4. Test the Hypothesis Develop a controlled experiment,an experiment that contains only one experimental variable.

18. Variables A variableis a quantity that can have more than a single value. • For example, if you set up an experiment to determine which of three fertilizers helps plants to grow the biggest, possible variables could include plant type, amount of sunlight, amount of water,room temperature, type of soil, and type of fertilizer.

19. Variables

20. Variables It is important to control variables because if several variables are changed in the experiment, researchers can’t easily tell which variable is responsible for any results they observe. The variable that is deliberately changed is called the independent variable (also called the manipulated or experimental variable).

21. Variables The variable that is observed and that changes in response to the independent variable is called the dependent variable(also called the responding variable).

22. Controlled Variables- all variables in the experiment that are kept the same

23. Constants A factor that does not change when other variables change is called a constant; they are controlled variables. • For example, if in an experiment you use the same soil and type of plant, the same amount of sunlight and water, and keep the same temperature, these are all constants.

24. Control and Experimental Groups Typically, an experiment is divided into control and experimental groups when possible. Any group exposed to the independent variable is part of the experimental group. The control group is exposed to all of the same conditions as the experimental group except for the independent variable. .

25. Constants and Controls • In the sample experimental data below, plant D was not fertilized. This plant is a control, the standard by which test results can be compared.

26. Designing Controlled Experiments In the marsh grass experiment, the researchers selected similar plots of marsh grass. All plots had similar plant density, soil type, input of freshwater, and height above average tide level. The plots were then divided into control and experimental groups.

27. Designing Controlled Experiments The researchers added nitrogen fertilizer (the independent variable) to the experimental plots. They then observed the growth of marsh grass (the dependent variable) in both experimental and control plots.

28. Collecting and Analyzing Data Scientists record experimental observations, or data. There are two main types of data: quantitative data and qualitative data.

29. Quantitative Data- deals with numbers; it is data which can be measured Ex>length, height, area, volume, weight, speed, time, temperature, humidity, cost, sound level Quantitative  Quantity

30. Collecting and Analyzing Data In the marsh grass experiment, it could include the number of plants per plot, plant sizes, and growth rates.

31. Qualitative Data- deals with a description; it is data that can be OBSERVED but not measured Ex>colors, textures, smells, tastes, appearance Qualitative  Quality

32. Collecting and Analyzing Data In the marsh grass experiment, it might include notes about foreign objects found in the plots, or whether the grass was growing upright or sideways.

33. There are 30 students in the class. Quantitative

34. The freshman class has positive school spirit. Qualitative

35. This coffee has a serving temperature of 150oF. Quantitative

36. Bobby’s coffee is in an orange mug. Qualitative

37. 5. Analyze Data & Draw Conclusions Analyze experimental results,record observations, and organize data into graphs & tables

38. Drawing Conclusions The original hypothesis is reevaluated and revised; new predictions are made, and new experiments are designed. Data is never changed to suit a hypothesis. Hypotheses may have to be revised and experiments redone several times before a final hypothesis is supported and conclusions can be drawn.

39. Drawing conclusions Experiments must be reproducible and produce consistent results.

40. Suppose in an experiment that after several days, fertilized plants grow between 2 and 3 cm each day. If the unfertilized plant did not grow from its initial size, 10 cm, you might conclude from data that the growth of the fertilized plants was due to the fertilizer.

41. In the marsh grass experiment, analysis showed that marsh grasses grew taller than controls by adding nitrogen.

42. Being Objective • A bias occurs when what the scientist expects changes how the results are viewed. This expectation might cause a scientist to favor results from one trial over those from other trials. Scientists strive to be objective, but when science is applied in society, it can become personal rather than scientific.

44. Detecting Bias- 3 main types of bias A. incomplete information B. influencing or convincing the reader C. past experience influencing thinking 1. The pollution in our river is caused by the big factory upstream. The people who own the factory are only interested in making money. They don’t care about the environment at all. I heard about them from my friend Barry, and he knows what he’s talking about. 2. Every morning, my grandfather’s rooster crows when it is still dark. About five minutes later, the sun comes up. I don’t know how it works, but my grandfather’s rooster is responsible for the sunrise! 3. On the Internet, I learned about a place where aliens have secretly landed a spaceship on Earth. They’re going to take over the world, and when they do, they’ll put all of the redheaded people like me in charge. You’d better be nice to me! 4. Our new science textbook will be terrific! I have used other textbooks by the same company, and they are always well-written and accurate. One of the teachers at our school says this is the best textbook she’s ever used.

45. Using the Scientific Method

46. Example 1 I observe that when I buy the bargain brand insecticide, that insects do not die as quickly as when I buy the name brand. State the Problem: Is Raid the best insecticide on the market?

47. Research: Find information on the topic in books, the Internet, calling a customer service rep. for the product

48. Hypothesis: If Raid is the best insecticide on the market, then it will kill insects 50% faster than three other insecticides.

49. Test the hypothesis in a controlled experiment • Spray 4 separate containers with equal amounts of 4 different insecticides (one of which is Raid). Add equal amounts of the same type of insects to each container. Place them side-by-side and count how many insects remain alive each minute

50. Data