# Variables Data B Notes Strategy If you are

Variables & Data

B) Notes Strategy! If you are comparing things, put them next to each other. Independent Variable Dependent Variable Controlled Variable

Which is easier to compare? Set #1 Apples Oranges Cherries Oatmeal Juice Coffee Hot Pockets Candy Set # 2 Oranges Coffee Candy Hot Pockets Spaghetti Juice Oatmeal Cereal Apples Set # 1 Apples Oranges Cherries Oatmeal Juice Coffee Hot Pockets Candy Set #2 Oranges Coffee Candy Hot Pockets Spaghetti Juice Oatmeal Cereal Apples

A) 3 Kinds of Variables 1. 2. 3. Independent Variable Dependent Variable Controlled Variable

3 Kinds of Variables 1. 2. 3. Independent Variable Dependent Variable Controlled Variable

C) Independent Variable – something that is changed by the scientist ◦ What is tested ◦ What is manipulated

D) Add a picture 1. 2. 3. Independent Variables Dependent Variables Controlled Variables Independent Variable Definition Picture Independent Variable – something that is changed by the scientist • What is tested • What is manipulated Dependent Variable Controlled Variable

Add your own example from your experience: Independent Variable – something that is changed by the scientist ◦ What is tested ◦ What is manipulated Water and acid affect on shells

3 Kinds of Variables 1. 2. 3. Independent Variable Dependent Variable Controlled Variable Independent Variable Definition Independent Variable – something that is changed by the scientist • What is tested • What is manipulated Picture Example What was added to the shells e. g. acid. Dependent Variable Controlled Variable

3 Kinds of Variables Dependent Variable – something that might be affected by the change in the independent variable ◦ What is observed ◦ What is measured ◦ The data collected during the investigation

3 Kinds of Variables 1. 2. 3. Independent Variable Dependent Variable Controlled Variable Definition Picture Example Independent Variable Dependent Variable Independent Variable – something that is changed by the scientist • What is tested • What is manipulated Dependent Variable – something that might be affected by the change in the independent variable • What is observed • What is measured • The data collected during the investigation 12. 4 g What was added to the shells e. g. acid. bubbles Controlled Variable

3 Kinds of Variables Controlled Variable – a variable that is not changed ◦ Also called constants ◦ Allow for a “fair test” Not Changed

3 Kinds of Variables 1. 2. 3. Independent Variable Dependent Variable Controlled Variable Definition Picture Example Independent Variable Dependent Variable Independent Variable – something that is changed by the scientist • What is tested • What is manipulated Dependent Variable – something that might be affected by the change in the independent variable • What is observed • What is measured • The data collected during the investigation Controlled Variable – a variable that is not changed • Also called constants • Allow for a “fair test” 12. 4 g What was added to the shells e. g. acid. bubbles the shells

Let’s use your Variables Chart to analyze a new experiment! Independent Variable? Dependent? What are all the variables that are kept the same, the controlled variables?

We need to have a control group. Experimental Group = test groups that receive treatment with Independent group Control Group = test group that does NOT get treated with Independent variable Independent Variable – sunlight Dependent Variable – plant height Gets treatment with Independent Variable Experimental Group No treatment with Independent Variable no sunlight Control Group

We need to have a control group. Experimental Group = test groups that are treated with the Independent variable Control Group = group that is NOT treated with the Independent variable Independent Variable – sunlight Dependent Variable – plant height Experimental Group Gets treatment with Independent Variable No treatment with Independent Variable (no sunlight) Control Group

Results: Data Tables Group Day 1 Day 3 Day 5 Day 7 A (Control Group) __10__ hours sunlight 5 cm 10 cm 15 cm 20 cm B experimental Group __5__ hours of sunlight 5 cm 7 cm 10 cm 15 cm C (experimental group) __0__ hours of sunlight 5 cm 3 cm “Raw” Data

Analyzing Data – Making sense of the data Bar Charts highlight comparisons Dependent Variable Growth in cm Groups (Independent Variable) Hours of Sunlight

Analyzing the Data Line graphs show trends Relationships

Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle. What are the variables in this example?

What was the independent variable? Ages of the students ◦ Different ages were tested by the scientist

What was the dependent variable? The time it to put the puzzle together ◦ The time was observed and measured by the scientist

What was a controlled variable? Same puzzle ◦ All of the participants were tested with the same puzzle. ◦ It would not have been a fair test if some had an easy 30 piece puzzle and some had a harder 500 piece puzzle.

Another example:

An investigation was done with an electromagnetic system made from a battery and wire wrapped around a nail. Different sizes of nails were used. The number of paper clips the electromagnet could pick up was measured.

Independent variable: Sizes of nails ◦ These were changed by the scientist

Dependent variable: Number of paper clips picked up ◦ The number of paper clips observed and counted (measured)

Controlled variables: Battery, wire, type of nail ◦ None of these items were changed

The higher the temperature of water, the faster an egg will boil.

Independent variable – temperature of water Dependent variable – time to cook an egg Controlled variable – type of egg

Last one:

The temperature of water was measured at different depths of a pond.

Independent variable – depth of the water Dependent variable – temperature Controlled variable – thermometer

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