The Scientific Method

The Scientific Method

Scientists use the scientific method to investigate natural occurrences and phenomena.

The scientific method is a way to go about solving a problem.

There are about six steps of the scientific method

Step 1: Ask a Question

The first step in this method is to ask a question.

Scientists make observations about the world around them, and with these observations, they form questions.

This question can be solved with experimentation.

Often scientists will also do research to find out more about there observations.

Good Scientific Questions

Have real answers. Often the answer is “yes” or “no”.

Are testable. You could design an experiment or take measurements to find

answers.

Have a hypothesis that is falsifiable. This means your experiment could show that your hypothesis

(and that is okay!).

Are interesting!

Based on prior knowledge.

Can lead to other good questions.

How does _____ affect ______?

When asking a question, it is important we ask it in a particular way.

It is worded so that we find out what we are trying to learn.

An example of this would be “How does the color of a light bulb affect the growth of grass seeds?”

What are some examples you can give?

Writing Scientific Questions

Are roses prettier flowers than tulips?

Can daisies grow in different types of soils?

How can we make cut flowers stay fresher for a longer period of time?

Writing Scientific Questions

Andre and Marie love popcorn, but they don’t have much money to spend. They want to decide if more expensive brands of popcorn really pop better than others.

Step 2: Make a Hypothesis

The next step is to form a hypothesis!

A hypothesis is essentially a prediction. It’s an educated guess about what you think will happen in an experiment.

How does the color of a light bulb affect the growth of grass seeds?

How would we form our hypothesis?

If __________ , then __________, than __________.

Our hypothesis should also be asked in a particular way.

“If I ….. (do something), then…. (this will occur)”.

For example, we could say “If I grow grass seeds under green light bulbs, then they will grow faster, than plants growing under red light bulbs.”

Writing Hypotheses

Your cat just had six kittens. There’s a new kitten chow on the market that claims to be healthier for young kittens. Your family has raised kittens before and fed them a different brand of food. You’d like to find out for yourself.

Writing Hypotheses

How does the type of water (salt water vs. fresh water) affect the rate at which it will freeze?

How does the type of music (jazz, classical, or rock) affect the time it will take to quiet a crying baby?

Independent Variable

Independent variable: This is the part of your experiment that you will test (vary) to answer your hypothesis.

In our example, the independent variable would be the different colors of the light bulbs.

Dependent Variable

The dependent variable is what occurs in response to the changing independent variable… It depends on the IV.

In our grass seed example, the dependent variable would be how much the grass seeds grow.

Control Group

The control should be the part of the experiment where you do not include the independent variable.

It is used as a COMPARISON!

In our example, grass seed growing under the white (uncolored) bulb would be your control. The control lets you compare results in an experiment.

Determining Variables How does the type of water (salt water vs. fresh

water) affect the rate at which it will freeze? Independent Variable: Dependent Variable: Control group:

How does the type of music (jazz, classical, or rock) affect the time it will take to quiet a crying baby? Independent Variable: Dependent Variable: Control group:

Determining Variables

Example: At-risk children who attend Head Start get better grades in reading in second grade. Independent Variable: Dependent Variable: Control group:

Example: Plants that get regular water grow taller. Independent Variable: Dependent Variable: Control group:

Determining Variables

Example: Athletes who do not get enough sleep the night before will not run as fast the next day. Independent Variable: Dependent Variable: Control group:

Example: Puppies that are given vitamins gain more weight. Independent Variable: Dependent Variable: Control group:

Putting it all Together

1: Ask a question-How does ____ affect ____?

Where should our Independent and Dependent variables go?

2: Make a hypothesis- If _____ , then _____.

Where should our Independent and Dependent variables go? Control group?

Step 3: Conduct an Experiment! This is the fun part! Design a test or

procedure to find out if your hypothesis is correct. In our example, you would set up grass seeds under a green light bulb and seeds under a red light bulb and observe each for a couple of weeks.

It’s very important to write down exactly what you do for your experiment, step by step. This is called a protocol.

Protocol

We write a protocol so that others will be able to replicate an experiment if they choose to do so.

Scientists write protocols so that other scientists may peer review their work.

A well-written protocol will allow others to successfully replicate the results of your experiment.

Identify Constants

A constant is anything we keep consistent in our experiment.

For example, although we are changing the color of the light bulbs, we would keep the wattage the same.

What are some examples of other constants for our grass seed experiment?

For our fry experiment?

Step 4: Collect Data

This is what makes science, science! Writing it down!

We make observations about what is happening in our experiment.

This includes our protocol, and lists of required equipment and instruments necessary for the experiment.

Types of Data

Qualitative data Describes and characterizes Example: The pill bugs moved to the dark area in

the container. Example: The color of the background was purple.

Quantitative data Numbers, values, measurements Example: 16 pill bugs moved to the dark area in

the container. Example: Three of the pill bugs were active for 24

seconds during 1 minute.

Step 5: Analyze Information When you do experimental analysis, you

are looking at what happened during your experiment. You’ve been collecting data; now it’s time to analyze it!

Through data analysis, we can make conclusions about our hypothesis.

Use graphs and data tables to organize your data and draw conclusions.

Conclusion

In order to have a conclusion, you must review your information and data to check and see if your hypothesis is correct.

In our example, if the grass under the green light bulb grew faster, then we can assume our hypothesis was correct, and begin performing multiple tests.

It’s not “bad” if your hypothesis is wrong!

Step 6: Report Results

After we have finished analyzing the data and have formed a conclusion, we can share our results with other scientists!

This is how scientists share with others, in a process called peer review. Other scientists try to take what one has done, and replicate it successfully.