1. Determining Cause & Effect
To investigate how long it takes a sugar cube to dissolve (an "effect"), we consider the things (the factors) that could affect how fast this happens (the possible "causes”)
Such as
the temperature of the water
the amount of water
whether the cube is whole or crushed (the surface area)
whether the water is still or stirred

2. Designing Experiments
In a "well-controlled experiment”, only ONE of the factors can be changed
the other factors must be kept the same
that is, they must be “controlled”
If two factors are changed, you can't determine which one is the "cause" of the "effect" that you observed!!

3. Experimental Terms Independent variable Control(s) Dependent variable
the factor that is intentionally changed
at the beginning of the experiment
it is the "input" for the experiment
it is the "cause" being investigated
Control(s)
the factors that are kept the same
(sometimes a group that is used for comparison)
Dependent variable
the measured result
at the end of the experiment
it is the "output" of the experiment
it is the "effect" being investigated

4. Data Tables
When we record data from an experiment, we organize the data table in a specific way:
The independent variable goes in the first (or left-hand) column
The dependent variable goes in the second (or right-hand) column
When we consider how something changes “with the passage of time”, time is the independent variable

5. Constructing Graphs Assign the data to the axes of the graph
The independent variable goes on the x axis
The dependent variable goes on the y axis
Orient the graph paper so the data set with the greater range of values is the long way
Draw and name the axes
Leave about 1 inch below the x axis and to the left of the y axis
Include the units of measurement in the axis name

6. Constructing Graphs – cont’d
Scale and label the axes
Divide the data range by the “available squares”
Round up to a scale that will make plotting the data easier to do
Plot the data as points on the graph
Draw a line or curve that shows the data trend
“Best Fit” line or curve
“Point-to-Point” line or curve
Label the graph so the data relationship is shown