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.
There are many types of graphs that can be used to portray distributions of quantitative variables. The upcoming sections cover the following types of graphs: (1) stem and leaf displays, (2) histograms, (3) frequency polygons, (4) box plots, (5) bar charts, (6) line graphs, (7) scatter plots (discussed in a different chapter), and (8) dot plots.