Scientific Method


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Notes on the Scientific Method

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Scientific Method

  1. 1. Nature of Science Methods of Scientific Study
  2. 2. Nature of Science Methods of Scientific Study aka Scientific Method
  3. 3. A discipline to investigate and understand nature, explain events in nature, and use those explanations to make useful predictions. Organized way of using evidence to learn about the natural world. Nature of Science What is Science?
  4. 4. Nature of Science How Scientists Work Scientists have a set of steps that are followed in research. Problem Hypothesis Experiment Observations Record Data Conclusions Communicate Results
  5. 5. Nature of Science Steps of Scientific Method 1. Problem 2. Hypothesis 3. Experiment 4. Observation 5. Record Data / Repeat Experiment 6. Conclusion 7. Communicate Results 1. Problem/Question 2. Observation/Research 3. Hypothesis 4. Experiment 5. Record Data / Repeat Experiment 6. Conclusion 7. Communicate Results
  6. 6. Problem: Develop a question or problem that can be solved through experimentation. Nature of Science Problem
  7. 7. Nature of Science Problem Maggots on Meat! Hypothesis: Spontaneous Generation
  8. 8. Nature of Science Problem Francesco Redi (1626- 1697) set out to disprove the theory of spontaneous generation.
  9. 9. Nature of Science Louis Pasteur (1822- 1895)
  10. 10. Nature of Science So what was the difference between Redi and Pasteur? Wikipedia Article on Spontaneous Generation
  11. 11. Observation/Research: Make observations and research your topic of interest. All evidence in scientific study is based on observations. ● Observations - uses one or more senses. (sight, hearing, touch, smell, and taste). ● Information gathered from observations is called data. Nature of Science Observations
  12. 12. ●Two types of observations: ● Quantitative: Involves numbers (e.g. counting or measuring ● Qualitative: A characteristic that cannot be counted or measured regularly (e.g. color or texture). Nature of Science Observations
  13. 13. Nature of Science Observations vs. Inference Statement Observation Inference Object A is round and orange X Object A is a basketball X Object C is round and black and white X Object C is larger than Object B X Object B is smooth X Object B is a table-tennis ball X Each object is used in a different sport X X Object A = Basketball Object B = Table-tennis ball Object C = ?
  14. 14. So let’s make some observations! Write down anything that your senses picked up during this demonstration. Nature of Science Observations
  15. 15. Formulate a Hypothesis: Predict a possible answer to the question or problem. Example: If soil temperature rises, then plant growth will increase. Nature of Science Hypothesis
  16. 16. Nature of Science Hypothesis A teacher collected some beetles from a rotting log and placed them in a container of dry oatmeal in her classroom. She kept the box covered with a light cloth so that the beetles could not escape. She also asked one of her students to add potato and apple pieces once a week to provide food and moisture for the beetles. After several weeks, the students reported that there were some strange-looking, wormlike organisms in the container. ● Formulate a hypothesis that might explain the presence of the “worms” in the container. ● How could you test your hypothesis?
  17. 17. Nature of Science Controlled Experiments Setting up Controlled Experiments ● Hypotheses should be tested by experiment by which only one variable changes. ● Variables: Temperature, Time, Light, amount grown, etc. ● Two Types of Variables ● Manipulated - Variable that is deliberately changed. (Independent) ● Responding - Variable that changes due to manipulated variable. (Dependent)
  18. 18. Nature of Science Controlled Experiments Setting up Controlled Experiments ● Developed procedure ○ Cannot be vague, must be extremely detailed. ● Materials list ○ List exactly what you used and how much. ● The outcome or results must be measurable. ○ If you cannot measure it, then it is not a controlled experiment.
  19. 19. Nature of Science Data / Results Record Results or Data Collection ● Scientists keep written records of their observations. ● Data is sometimes written but can be stored on computer for easy access. ● Make sure that you make good observations and quantifiable measurements.
  20. 20. Nature of Science Data / Results ● Data that is collected is used to draw conclusions. ● Data must be consistent. ● Modify procedure if need be. ● Confirm your data/results by retesting. ○ Never only test a single time.
  21. 21. Nature of Science Data / Results ● The best way to analyze data is with tables and charts.
  22. 22. Nature of Science Conclusion Conclusion: Include a statement that accepts or rejects the hypothesis. Make recommendations for further study and possible improvements to the procedure.
  23. 23. Nature of Science Conclusion Based on the following hypothesis and data, what can you conclude? Hypothesis: If states do not require drivers to wear seat belts (secondary law), then younger age drivers will be less likely to wear their seat belt compared to older aged drivers.
  24. 24. Now let’s use our knowledge of the scientific method to a realistic example. Nature of Science John watches his grandmother bake bread. He ask his grandmother what makes the bread rise. She explains that yeast releases a gas as it feeds on sugar.
  25. 25. John wonders if the amount of sugar used in the recipe will affect the size of the bread loaf? Nature of Science Problem/Question
  26. 26. John researches the areas of baking and fermentation and tries to come up with a way to test his question. He keeps all of his information on this topic in a journal and uses the Experimental Design Diagram to help him in his investigation. Nature of Science Observation/Research
  27. 27. Hypothesis: If more sugar is added, then the bread will rise higher. Nature of Science Hypothesis
  28. 28. The independent, or manipulated variable, is a factor that’s intentionally varied by the experimenter. John is going to use 25g., 50g., 100g., 250g., 500g. of sugar in his experiment. Nature of Science Variables
  29. 29. The dependent, or responding variable, is the factor that may change as a result of changes made in the independent variable. In this case, it would be the size of the loaf of bread. Nature of Science Variables
  30. 30. In a scientific experiment, the control is the group that serves as the standard of comparison. The control group may be a “no treatment" or an “experimenter selected” group. The control group gets the same treatment as the experimental group. ALL EXPERIMENTS MUST HAVE A CONTROL GROUP Nature of Science Controls
  31. 31. What are some things that John is going to keep the same in all trials of his experiment? Nature of Science Constants
  32. 32. A clear procedure needs to be written first before the experiment is carried out. Data is collected when carrying out the procedure and placed in a table. Data should ALWAYS be recorded into a table. (Makes it easy to read and interpret) Nature of Science Procedure
  33. 33. John decide to test his hypothesis again, but adjusting his experiment a little bit. Nature of Science