Variables in a Science Experiment

Relationships Among Variables In this section, you will learn to interpret cause and effect relationships among data, and to use trends to make predictions.

Cause and Effect Relationships Among Variables

A change in the manipulated/independent variable will cause a change in the responding/dependent variable.

For Example: Changing height of a ramp will cause a K'nex car to go faster or slower.

Manipulated/Independent Variable = Height of the Ramp

Responding/Dependent Varialbe = Seconds to Reach the Finish Line

K'nex Cars on a Ramp

Another Example

True or False

According to the graphs, the Catawba River has less chemical pollutants and more organisms than Young’s Creek. This means that chemical pollution in Young’s Creek may have caused a reduction of organisms in that body of water.

This is True.

Patterns of Change

Patterns of change (trends) can be used to make predictions. For Example: A decrease in seagrass over many years will likely lead to more coastal erosion

http://pubs.usgs.gov/of/2008/1206/html/figs/fig4_1.html

Let's Practice

As a K’nex carries an increased load, it will need an increase in the amount of force needed to make the car move. Looking at the graph what can you predict about the number of washers needed to move a car that is carrying 3 blocks? It will need _____ washers.