The Iceman’s Last Journey NOS Lesson 3 The Iceman’s Last Journey

A Controlled Experiment What does it mean to have a controlled experiment?  Everything is kept constant (the same) except the independent variable If we change more than one variable, then we don’t know that the results are from the variable we are trying to test for!

First We Must Understand Variables! Variable- any factor that can have more than one value In controlled experiments there are 2 kinds of variables: _____________ and ____________ variables. Independent Dependent

The Independent Variable The factor that you want to test. It is changed by the investigator to observe how it affects a dependent variable Example: The amount of light each room of plants receives Light Room Dark Room

The Dependent Variable The factor you observe or measure during an experiment Example: How high the plants grow due to the amount of light they are given Light Room Dark Room

When the independent variable is changed, it causes the dependent variable to change The dependent variable depends on the independent variable

A Controlled Experiment Has 2 Groups: The ______________ group and the ________ group Experimental Control

The Experimental Group Used to study how a change in the independent variable changes the dependent variable The “experiment” is happening on this group

The Control Group Contains the same factors as the experimental group, but the independent variable is not changed The group that stays the same so we can compare it to the experimental group

Why Do Scientific Experiments Require a Control Group? Without a control, you can’t tell if your results (dependent variable) are from the variable you are testing (independent variable) or from another factor We must have it to compare with the experimental group!

A Controlled Experiment Has: Independent Variable Dependent Variable Experimental Group Control Group