The Scientific Method. Scientific Method. Goal: to solve a problem or to better understand an observed event. Can be used for big scale or everyday problems For example: What is the best energy efficient car brand to reduce carbon dioxide emissions?
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The scientific method is the only scientific
way accepted to back up a theory or
This is the method on which all research
projects should be based.
The Scientific Method is used by researchers
to support or disprove a theory.
Information you obtain through your senses.
Things you “wonder” about
Sample observation: I wonder why the strawberry plants in my back yard grow faster then the strawberry plants in my front yard.
I wonder why I do better on my math tests when I write in red ink.
Combine your observation into a question.
Should be a testable questions that can’t be answered with “yes” or “no”
Example: How does strawberry plant location effect plant growth?
How does the ink color used on math tests effect my grade?
A statement based on observations
Must be in if/thenformat (important for CAPT)
For it to be useful it must be testable
Sample: If the strawberry plants are planted in the front yard (increased sunlight) then they will growth faster.
If red ink is used on math test then the performance on the test will increase.
Is there more then one way to state a hypothesis for this problem?
Try to write another hypothesis for this problem.
Must design an experiment that will test your hypothesis.
Experiment focuses on the Independent and Dependent Variable
Is is a good idea to test more then one variable at a time?
Method - You figure out a way to test whether
the hypothesis is correct. The outcome must be
Record and analyze data.
The independent variable is the variable that is purposely changed. It is the manipulated variable.
The dependent variable changes in response to the independent variable. It is the responding variable. Usually something that can be measured: time, distance, weight/mass.
Independent Variable IV ( Something“I” Change):
Dependent Variable DV (Measured):
What are constants in an experiment?
- Factors that are kept the same and not allowed to change.
It is important to control all but one variable at a time to be able to interpret data
Keeps your results valid/accurate
Apple juice lab…50ml of apple juice, 10 grams of each enzyme.
Example…if we were testing different baseball bats to see which bat hit the furthest what are things we would need to control or keep constant?
Same person hitting
Same tee to hit off/or person pitching
THIS IS VERY DIFFERENT FROM CONSTANT OR CONTROLLED VARIBLES!
The Control is the part of experiment that DOES NOT experience the independent variable.
It is the “normal” conditions.
You test a control so your have something to compare your results too.
NOT all experiments will have a control.
room temp, water cup, etc.
Example: The effect of temperature on plant growth…what temperature would be the control group?
What is to be changed? -IV
What is to stay the same? – Constants/controlled variables
How are you going to measure it? DV
We use the metric system in science labs.
Used worldwide makes it easier to communicate results of an experiment to other countries.
Always include units in measurements.
Mass is measured in:
using a Triple Beam Balance
Volumes is measured in
Using a Gradualted
Length is measured in
Using a Metric Ruler
Temperature is Measured in:
Degrees Celsius ( C )
Density is: Mass per unit volume
relative "heaviness" of objects with a constant volume.
Example: A rock is obviously more dense than a crumpled piece of paper of the same size.
A description of what you will use for your experiment, and how you will do it.
Be sure to include:
1. Obtain two of the same strawberry plants. Label one plant “A” and one plant “B”
Before carrying out your experiments you must decided how you will record your data.
First design a data table
Include units in data table and enough room for all trials.
Title: The Effect of the independent variable on the dependent variable
Title: The Effect of the independent variable on the dependent variable *plug in your IV and DV depending on the experiment
Independent Variable – include units and an appropriate scale
What factors in your materials or procedure might have had an impact on your results?
Commonly - better job controlling outside variables example: same person should be reading the thermometer, ruler, timer etc.
Improvement of equipment
If your hypothesis is NOT support you can go back and revise it or propose a new one
BUT you must design a new experiment to test the new hypothesis.
Never alter your data to match your hypothesis!