Scientific Method

The Scientific Method Make Observations Ask a Question Form a Hypothesis Design an Experiment Record and Analyze Results Draw Conclusions

1. Make Observations The process of gathering information about events or processes Done in a careful, orderly way Use the senses: Sight, touch, hearing, smell, taste?

2. Ask a Question

3. Form a Hypothesis Hypothesis: a proposed explanation for a set of observations; An educated guess. A possible answer for your question. Inference: A logical interpretation of an observation based on prior knowledge or experience. Examples: Take water samples when you can’t test the entire lake You assumed that Ms. H took a bite out of a candle because the “thing” she ate was similar to what you know about candles

Question 1 Which of the following is a good hypothesis. Dogs like treats. If I give a dog a treat, it will be happy. Dogs that are fed eggs will have coats that are more shiny. Dogs that are fed treats and eggs will have coats that shiny coats and be happy.

4. Design an Experiment Use an experiment to test your hypothesis. Controlled experiment: Only one variable is changed. Manipulated (independent) variable: The variable that is changed. Responding (dependent) variable: The variable that changes in response to the manipulated variable. Controlled variables: Variables that do not change. Control Group: The group that shows what happens with no treatment (the normal result)

Question 2 You decide to clean the bathroom and notice that the shower is covered in a strange green slime. You spray half the shower with lemon juice and the other half of the shower with water. In this experiment what is the independent variable? The amount of times you spray the shower The time it takes to clean the shower The lemon juice The green slime

Question 3 You decide to clean the bathroom and notice that the shower is covered in a strange green slime. You spray half the shower with lemon juice and the other half of the shower with water. In this experiment what is the dependent variable? The amount of times you spray the shower The appearance of the green slime on the shower wall(s). The lemon juice sprayed on one half The water sprayed on one half

Question 4 You decide to clean the bathroom and notice that the shower is covered in a strange green slime. You spray half the shower with lemon juice and the other half of the shower with water. In this experiment what is the control group? The amount of times you spray the shower The appearance of the green slime one each side The lemon juice sprayed on one half The water sprayed on one half

Data: Information from Observations Quantitative Data: Numbers, Counting, Measuring Example: “The animal weighs 50 pounds.” Qualitative Data: Descriptive, Characteristics that can’t be counted. Example: “The animal seems healthy.”

Question 5 If I measure the height of everyone in this class, what type of data am I collecting? Quantitative Qualitative What is an example of qualitative data I could collect from our class?

Graphing Data Dependent Variable Independent Variable

More Graphs Your turn: Sketch a graph You are conducting an experiment to measure the effect of jumping rope on Ms. H’s heart rate (after 0, 1, 5, and 10 minutes). What would be your dependent and independent variables? On what axis would they be on your graph?

5. Record and Analyze Results Keep written records of observations/ data Drawings Graphs Charts Keep detailed records of the experiment so that it can be repeated by other scientists.

6. Draw Conclusions Can either accept or reject the hypothesis. If data agrees we accept If data disagrees we can reject. If data is unclear we may choose to re-test or alter our hypothesis. We cannot PROVE anything true in science We can only support and then we continue to look for more evidence.

Discuss with a Partner: -Discuss the diagram below and what it means to you. -What do you think represents the scientific method more accurately: a. series of steps or b. a cycle? Why?

Theory Experiments must be repeated many times before a hypothesis is accepted as a theory. Theory : a well-tested explanation that unifies a broad range of observations. Example: the theory of biogenesis: new organisms come from existing organisms. Theories are used to make predictions about new situations No theory is considered absolute truth. As new evidence is discovered, scientists change or revise theories. “The Earth is flat” “The Earth is round”

Theory vs. Law Law: describes something that consistently happens (generalizes a body of explanations). Example: Newton's Law of Gravity. Newton could use this law to predict the behavior of a dropped object, but he couldn't explain why it happened. Theory: explains WHY something happens There can be theories that explain why certain laws happen.

Questions 6 Which of the following is an example of a theory If I throw a penny off the Empire State Building it will fall to the ground. Objects will fall toward the surface of the Earth because there are forces that attract all objects to all other objects. In a poll taken at WHS it was found that most people listed purple as their favorite color.

Science is… A way of knowing. An ongoing process. Limited. It can’t help you decide whether a painting is beautiful or not.