# The Scientific Method - PowerPoint PPT Presentation

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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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The Scientific Method

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### 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 Method

The scientific method is the only scientific

way accepted to back up a theory or

idea.

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 Method

• The Scientific Method involves 5 steps:

• Observation

• Question

• Hypothesis

• Method

• Result

### Make an Observation

Information you obtain through your senses.

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?

### 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….

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

Yes

Try to write another hypothesis for this problem.

Strawberry:

Ink:

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 Method

Method - You figure out a way to test whether

the hypothesis is correct. The outcome must be

measurable (quantifiable).

Record and analyze data.

### 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

Independent Variable IV ( Something“I” Change):

Strawberry:

Ink:

Dependent Variable DV (Measured):

Strawberry:

Ink:

### 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

### 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

Strawberry:

-

-

Ink Color

-

-

### CONTROL GROUPS or the CONTROL

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.

### 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 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

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.

### Units

Mass is measured in:

grams (g)

using a Triple Beam Balance

### Units

Volumes is measured in

liters (L)

cylinder

### Units

Length is measured in

meters (m)

Using a Metric Ruler

### Units

Temperature is Measured in:

Degrees Celsius ( C )

using a

Thermometer

### Units

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.

Brainpop Metric!

### 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

### 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

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

2.

### 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

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

### 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

### Graphs

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

• Comment on hypothesis.

• Was it SUPPORTED or NOT SUPPORTED

• Comment on all data Even if your hypothesis is Not Supported!

• Calculate the differences between the averages and comment on them.