Notes 1 SPI 0807.Inq.1 (Variables and Controls) Independent Variables in Experiments  Used with the scientific method Scientific Method (In Flow Chart Format)  Use independent variables when you test your hypothesis by doing experiments Press the Right Arrow Button to Advance through the Presentation!

Notes 2 Step 1: Make Observations Step 2: Ask A Question Step 3: Form A Hypothesis Step 4: Test The Hypothesis  By doing experiments Step 5: Analyze The Results Step 6: Draw Conclusions Step 7: Communicate results Scientific Method (In List Format) Variables and Controls in Experiments  Used with the scientific method  Use independent variables when you test your hypothesis by doing experiments (see step 4 above) SPI 0807.Inq.1 (Variables and Controls)

Experiments  In an experiment you measure a quantity and/or quality of something.  In an experiment you should conduct multiple trials  In other words you should duplicate your efforts several times Example:  Scientists could be testing a new cancer medicine to determine how effective it is  Scientists could be measuring the fuel consumption of a new type of car engine that could replace current engines Notes SPI 0807.Inq.1 (Variables and Controls) 3

In an experiment…  …you should only test for ONE key thing at a time When you repeat the experiment…  …only change this ONE key thing This one thing is called… Notes SPI 0807.Inq.1 (Variables and Controls) 4 Independent Variables

What is an independent variable? The one thing YOU change each time you duplicate an experiment Here is a simple memory trick to help you remember this.  Independent variable begins with the letter “I”  So remember the letter “I.”  Imagine yourself doing the experiment., and say this… “What is the ONE thing I would change when repeating the experiment?”  That one thing will be… Notes SPI 0807.Inq.1 (Variables and Controls) 5

Reminder: Example 01: So…what is the independent variable in this example? In other words, what is the one thing YOU would change each time you repeat your experiment? change each time you repeat the experiment Notes SPI 0807.Inq.1 (Variables and Controls) 6 The independent variable is the type of soft drink YOU The independent variable is the one thing You decide to do an experiment to determine the reason certain soft drinks are more popular that other soft drinks. You suspect that the popularity of the drinks is connected with the amount of sugar found in them. You decide to use Coke, Pepsi, and Dr. Pepper in this experiment. You first determine how much sugar each drink contains. Then you get 6 students to do a blind taste test with all 3 drinks.

Example 02: So…what is the independent variable in this example? In other words, what is the one thing YOU would change each time you repeat your experiment? A scientist is conducting an experiment to test how sunlight affects plant growth.  She places one corn plant 1 meter away from a sunlamp.  She places one corn plant 2 meters away from a sunlamp.  She places one corn plant 3 meters away from a sunlamp. Notes SPI 0807.Inq.1 (Variables and Controls) 7 The independent variable is the amount of sunlight as determined by the distance from the sunlamps

Example 03: So…what is the independent variable in this example? In other words, what is the one thing YOU would change each time you repeat your experiment? A student conducts an experiment with ten 8th grade students (5 boys and 5 girls). He uses 3 similar types of sour candy (Sour Skittles, Sour Patch Kids, and Warheads) in a series of 4 trials. He gives 1 piece of candy to each student and records their facial expressions as they eat it. Notes SPI 0807.Inq.1 (Variables and Controls) 8 The independent variable is the type of sour candy

Example 04: A student conducts an experiment to determine which type of glue works best for attaching two pieces of regular writing paper together. He uses 3 types of Elmer’s glue in a series of experiments (1) Liquid-washable, (2) Glue Stick-washable, (3) Glue Stick-nonwashable) He places the same amount of glue (2g) on each sheet of paper. Notes SPI 0807.Inq.1 (Variables and Controls) 9 The independent variable is the type of glue So…what is the independent variable in this example? In other words, what is the one thing YOU would change each time you repeat your experiment?

Example 05: A student conducts an experiment to determine which ink color in ballpoint pens will last the longest before running out. She uses 3 ink colors in 3 ballpoint pens in a series of experiments. (1) Black ink pen, (2) Blue ink pen, (3) Red ink pen) She copies text from his science book. She copies the same text over and over. She writes at the same speed. The room temperature remains the same. She writes on the same kind of paper. Notes SPI 0807.Inq.1 (Variables and Controls) 10 The independent variable is the color of ink So…what is the independent variable in this example? In other words, what is the one thing YOU would change each time you repeat your experiment?