Variables and Graphing
What is a Variable? Something that can be changed.
Independent Variable condition of an experiment that is changed to see how it will affect the dependent variable What is tested What is manipulated
Dependent Variable The quantity that responds to the changes in the independent variable What is observed What is measured The data collected during the investigation
Constant The standard in an experiment – which is NOT changed
Experimental Groups Sample that has the independent variable applied to it.
Control groups Sample that is treated like the other experimental groups except that the independent variable is not applied to it Provides a comparison group
Fill in Notes An independent variable is a variable whose value causes another variables value to change. A dependent variable is a variable whose value depends on or is determined by another variable.
Martha Example The independent variable is the gas because it causes a change in the price. The dependent variable is the money because it depends on how much gas is bought.
Jake Example The independent variable is the time because it causes a change in the number of miles. The dependent variable is the miles because it depends on how long Jake runs.
What is a graph? Visual display of info. or data Different kinds of graphs express different types of information
Line graph Shows a relationship where the d.v. changes due to a change in the i.v.
Bar graph Compares information collected by counting
Circle graph/pie chart Shows the relationship of parts to a whole. (%)
Rules for Graphing Identify: x-axis=i.v. (horizontal line) Y-axis =d.v. (vertical line) Choose the SCALE don’t fear the graph paper, fill it up!
3. Pick proper increments Choose values that are easily divided! All graphs do not have to begin at zero (0) – how big are the numbers you are using?
4. Label each axis – feet, seconds, etc.. Title the graph! The y-axis vs. x-axis 5. Create a Key! – if you are comparing data, then tell the reader what each line or color stands for