By definition the control in a science experiment is a sample that remains the same throughout the experiment. The control must remain the same or equal at all times in order to receive accurate results. You can have as many controls as necessary to achieve results.
Graphs are often an excellent way to display your results. In fact, most good science fair projects have at least one graph. For any type of graph: Generally, you should place your independent variable on the x-axis of your graph and the dependent variable on the y-axis.
Specific tips for line graphs. 1  The graphing tutorial gives specific instructions on creating scatter plots and regression lines. 2  Line graphs can be created with either the Line Graph type or with (XY) Scatter. 3  It is simpler to create a line graph with (XY) Scatter when your independent and dependent variables are in columns.