Identifying Variables and Forming a Hypothesis

Science Project 2013

Before we begin…Have your Science Project Workbook out,Turn to page 6, the Student Progress ReportFill in the following due dates:

I formed a hypothesis Due 9/27/13

I identified my variables for Research Due 9/27/13

Science Project Approval Form Due 10/4/13

Identifying VariablesA variable is a factor that can change in an

experimentIn a controlled experiment, only one

variable is manipulated, or changed at a time. For your Science Project, you will perform a controlled experiment and change only one variable at a time.

Types of VariablesThe independent variable is the variable

that YOU are changing in your experiment. It is sometimes called the manipulated variable. You will only have one independent variable.Example: If your question is “What effect does

the color of light have on the growth of plants?” you will be changing the color of the light. The light is your independent variable, and you are manipulating the color.

Types of Variables• The dependent variable is the factor that

changes as a result of the independent variable. This is the variable that you will be measuring. It is also known as the responding variable.Example: Using the same question “What

effect does the color of light have on the growth of plants?”, the variable that is being measured is plant growth. Plant growth is your dependent variable. The tool used to measure it will need to be ruler with centimeters.

Controlled variablesControlled variables are also known as

constants. These are the factors in an experiment that stay the same.

Since only one variable is manipulated in an experiment, you will have several constants.Using the same example: What types of things

will stay the same in the experiment about plants colors of light?

Your turn!Turn to page 8 in your Science Project

Workbook. On this page, you will identify all of the

variables about your topic. You are to have numbers 1-5 answered by 9/27/13.

Forming a HypothesisA hypothesis is a possible explanation for a

set of observations or answer to a scientific question. It must be testable!

Scientists often use the IF/THEN/BECAUSE format when writing a hypothesis. If I….(do this) then (this will happen) because (this is what I researched).

A good hypothesis not only states a prediction but also gives details about the experiment.

ExamplesExamples of good hypotheses:

If I change the color of light when growing plants, then I think the plant grown with the purple light will grow the most because purple is the color of light closest to UV waves emitted by the sun.

If I place Mentos in different types of soda, then I predict the Diet Soda will have the strongest chemical reaction because diet soda contains chemicals that react the most with the ingredients in Mentos.

These examples tell me the prediction as well as details about the experiment being performed. They also show reasoning based on research.

Non-ExamplesExamples of hypotheses that are not

acceptable:I think my design of paper airplane will fly the

farthest.If I grow a plant in different lights then it will

have an effect on them. If I drop Mentos in soda then it will have a

reaction.If I drop Mentos in soda then Mountain Dew

will have the best reaction because that is what Mythbuster’s used.

Your turn!Page 8 in your Science Project Workbook has

space at the bottom for you to try writing a hypothesis using different formats.

You have until 9/27/13 to have your hypothesis written on this page for approval.

Science Project Approval FormThe Science Project Approval Form is found

on page 9 of your workbook. Your approved hypothesis and variables are

written on this page after your teacher has reviewed page 8.

This page is to be filled out by you and signed by your parents by 10/4/13.