Topic: Nature of Topic: Nature of ScienceScience

MI: Scientific MethodMI: Scientific Method

What is the Scientific What is the Scientific Method?Method?

Universal approach to Universal approach to scientific problemsscientific problems

Steps of the Scientific Steps of the Scientific MethodMethod1.1. Define the problem Define the problem (?)(?)

2.2. Form a Form a hypothesishypothesis: : an educated guess an educated guess (I think….)(I think….)

3.3. Gather materials neededGather materials needed

4.4. Perform Perform a a controlled experimentcontrolled experiment to to test the hypothesistest the hypothesis

5.5. Make observations Make observations

6.6. Organize the results or data collectedOrganize the results or data collected

7.7. Draw a conclusionDraw a conclusion

Controlled Controlled ExperimentExperiment

- There must be 2 or more groups:There must be 2 or more groups:- Experimental groupExperimental group contains contains

the variablethe variable- Control groupControl group does NOT does NOT

contain the variablecontain the variable

Everything between the 2 groups Everything between the 2 groups must be exactly the same except must be exactly the same except for the variable!!!!!for the variable!!!!!

What is the What is the variablevariable?? The factor in the experiment that can The factor in the experiment that can changechange

2 types2 types– Independent variableIndependent variable the the ONEONE

factor that is factor that is DIFFERENTDIFFERENT between the between the experimental group and the controlexperimental group and the controlExamples: Examples: temperature, light, light temperature, light, light intensityintensity

– Dependent variableDependent variable influenced by influenced by the independent variablethe independent variableWhat you will measure / What you will measure / DATADATA or or results you observedresults you observed

What is the What is the control?control?

Separate setup exactly like the Separate setup exactly like the experimental group experimental group EXCEPTEXCEPT it it does not contain the variabledoes not contain the variable

What must be done to make the What must be done to make the results of an experiment reliable / results of an experiment reliable /

accurate / valid?accurate / valid?

REPEATREPEAT the experiment the experiment (without changing the control or (without changing the control or variable) and obtain the same variable) and obtain the same resultsresults

A larger sample sizeA larger sample size Only one variableOnly one variable

What is a theory?What is a theory?

A hypothesis supported by A hypothesis supported by many experiments many experiments

Thought to be true but can be Thought to be true but can be changedchanged

ExampleExample Sandy wants to test the effect of rap Sandy wants to test the effect of rap

music on pea plant growth. She plays music on pea plant growth. She plays loud rap music 24 hours a day to a loud rap music 24 hours a day to a series of pea plants grown under light, series of pea plants grown under light, and watered every day. At the end of and watered every day. At the end of her experiment she concludes rap is her experiment she concludes rap is conducive to plant growth. Her teacher conducive to plant growth. Her teacher grades her project very low. grades her project very low. Why???????Why???????

Sandy returns to her experiment, but this Sandy returns to her experiment, but this time she has a separate group of plants time she has a separate group of plants under the same conditions as the rapping under the same conditions as the rapping plants, but with soothing Led Zeppelin plants, but with soothing Led Zeppelin songs playing. She comes to the same songs playing. She comes to the same conclusion as before, but now has a basis conclusion as before, but now has a basis for comparison. Her teacher gives her for comparison. Her teacher gives her project a better grade.project a better grade.

1.1. Give the problem and hypothesis of this Give the problem and hypothesis of this experiment.experiment.

2.2. What was the independent variable?What was the independent variable?

3.3. What was the dependent variable?What was the dependent variable?

4.4. What should be done to make the results of What should be done to make the results of Sandy’s experiment more reliable?Sandy’s experiment more reliable?