Bellwork 8/15/17 What are factors that can be changed in an experiment? What are two different kinds of variables?

Lesson 1-2 Variables

“I can”… Learning Targets: Identify the independent and dependent variable when given an experiement.

Important terms to know: Hypothesis Variables: Independent Variables Dependent Variables Control Groups Constants Trials

Variables are factors that can be changed in an experiment. Hypothesis The hypothesis is an educated guess about the relationship between the independent and dependent variables. Variables are factors that can be changed in an experiment.

Variables Variables are things that vary and change in an experiment

Variables In any experiment there are 2 types of variables: an independent (or input) variable a dependent (or outcome) variable Let’s look at each type….

Independent Variable (input)……. The independent variable is the one that is purposely changed in an experiment. John changed the amount of sugar in his experiment.

Dependent Variable (outcome) The dependent is the factor that may change as a result of changes made in the independent variable. In this case, it would be the size of the loaf of bread.

What does all that mean??? It’s simple…The Dependent Variable is always “Dependent” on what is done to the Independent Variable…. This is where you get your data

The control group may be a In a scientific experiment, the control is the group that serves as the standard of comparison. The control group may be a “no treatment” group.

All experiments should have a control group. The control group is exposed to all of the same conditions as the experimental group, except for the variable being tested. All experiments should have a control group.

Control Group For example: Because his grandmother always used 50g of sugar in her recipe, John is going to use that amount in his control group.

Constants The constants in an experiment are all the factors that remain the same.

Can you think of some constants for John’s experiment?

Constants They might include: All of the ingredients used in the bread recipe, oven used, rise time, brand of ingredients, cooking time, type of pan used, air temperature and humidity where the bread was rising, oven temperature, age of the yeast…

Trials “Trials” are the number of times you expose the experimental group to the variable being tested. Patrick is going to blow bubbles using the same brand bubble gum 3 times.

Sample Problem: Homer notices that his shower is covered in a strange green slime. His friend Barney tells him that coconut juice will get rid of the green slime. Homer decides to check this out by spraying half of the shower with coconut juice. He sprays the other half of the shower with water. After 3 days of "treatment" there is no change in the appearance of the green slime on either side of the shower.

Answers… What is the independent variable? Coconut juice What is the dependent variable? Cleanliness of the shower curtain

Answers cont’d What variables are controlled? Shower curtain, amount of space treated, time treated What should Homer’s conclusion be? The coconut juice was ineffective. There was no change in the appearance of the green slime on either side of the shower.