1. Scientific Method Notes, 9/8/12 Science is a Search for Knowledge

2. 1. Gather Information. Make Observations using your 5 senses. Steps of a Scientific Method 2.Ask questions and define the problem. Observations make us ask questions about what we experience. Science uses evidence to answer testable questions.

3. 3. Make a Hypothesis Observations and questions lead to possible solutions. A hypothesis is a possible explanation that is based on observation and seeks to answer the question. A valid hypothesis is in the form of an if, then statement

4. 4. Test the hypothesis (Experiment) A controlled test of a hypothesis is called an experiment. A valid experiment has two variables (things that change) and a control.

5. Variables Any valid experiment has only two things that change - (The independent variable and dependent variable) The independent variable is manipulated. It is the thing in the experiment that you directly change! The dependent variable changes in response the independent variable. It is the thing that you measure!

6. Variables

7. Constant Variables Any valid experiment will only have one variable that changes. All other things that could change MUST be kept the same. the unchanging variables are called constants or constant variables.

8. The Control Group One test group (the control group) is not exposed to the tested effect (variable). Another test group is exposed to the tested effect (variable). Keep a control group for comparison.

9. Control and Variable What happens when a fire fly gene (the variable) is added to tobacco genes? This is the test plant.

10. Quick Write! Describe an experiment to test the effectiveness of a fertilizer on tobacco plant growth. Define the independent and dependent variables, your control group, and three constants.

11. 5. Analyze Data and Make Conclusions The measurements and observations made during the experiment are called data. Data is evidence to support the hypothesis. Data must be measurable in someway. Data cannot be an opinion or emotion.

12. Data Cont’… Look at data for patterns and trends. Graphs and charts make patterns more visible. Use the numerical data to support your conclusions!

13. Conclusions Conclusions are only valid if data supports it. Reject the hypothesis if the data does not support the hypothesis.

14. Conclusions cont’... Error Analysis is part of conclusions. List only KNOWN errors in the measurements DO NOT list your guesses (e.g. “We might have....).

15. Theory When many hypotheses have a large body of data and support they are unified into a Theory.