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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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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?
    • What is the best acne medicine to use for my face?
the scientific method1
The Scientific Method

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.

the scientific method2
The Scientific Method
  • The Scientific Method involves 5 steps:
          • Observation
          • Question
          • Hypothesis
          • Method
          • Result
make an observation
Make an Observation

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.

ask a question
Ask a question

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?

f orm a hypothesis
Form a hypothesis

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.

hypothesis con t
Hypothesis con’t….

Is there more then one way to state a hypothesis for this problem?


Try to write another hypothesis for this problem.



test your hypothesis determine variables
Test your hypothesis/Determine variables

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?


the scientific method3
The Scientific Method

Method - You figure out a way to test whether

the hypothesis is correct. The outcome must be

measurable (quantifiable).

Record and analyze data.

variables variables are things that change or vary
VariablesVariables are things that change or VARY.

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.

sample experiments
Sample Experiments

Independent Variable IV ( Something“I” Change):



Dependent Variable DV (Measured):



constants or controlled variables in an experiment
Constants or Controlled Variables in an Experiment

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

examples of controlled variables or constants
Examples of Controlled Variables or Constants

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 ball

Same tee to hit off/or person pitching

control groups or the control


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.

examples of controls
Examples of Controls

room temp, water cup, etc.

Example: The effect of temperature on plant growth…what temperature would be the control group?

Room temp

3 important questions to ask yourself before designing an experiment
3 important questions to ask yourself before designing an experiment

“3 Musts”

What is to be changed? -IV

What is to stay the same? – Constants/controlled variables

How are you going to measure it? DV

measurement in labs
Measurement in Labs

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:

grams (g)

using a Triple Beam Balance


Volumes is measured in

liters (L)

Using a Gradualted



Length is measured in

meters (m)

Using a Metric Ruler


Temperature is Measured in:

Degrees Celsius ( C )

using a



Density is: Mass per unit volume

  • unit of measure : measured in grams per cubic centimetre, or g/cm3

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.

designing an experiment
Designing an Experiment

A description of what you will use for your experiment, and how you will do it.

Be sure to include:

  • Step by step
  • Definite amounts (50mL, 50g, 50cm)
  • Repeated Trials
  • Drawing of Apparatus (draw first will help you write steps)
increasing validity in an experiment
Increasing Validity in an experiment
  • Validity - how reliable/ accurate your results are.
  • Ways to increase validity
    • Follow procedures exactly as written
    • Be sure to control variables
    • Perform multiple trials
    • Add a control group if possible
procedure example
Procedure Example

1. Obtain two of the same strawberry plants. Label one plant “A” and one plant “B”


collect data
Collect data

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.

sample data table
Sample Data Table

Title: The Effect of the independent variable on the dependent variable

graphing data
Graphing Data
  • Two major types:
  • -Bar graph: IF WORDS use this!
  • -Line graph
    • IV goes on the X-axis
    • DV goes on the Y axis

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

drawing conclusions
Drawing Conclusions
  • Comment on hypothesis.
  • Comment on all data Even if your hypothesis is Not Supported!
  • Calculate the differences between the averages and comment on them.
conclusion possible experimental errors
Conclusion: Possible Experimental Errors

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!