The three basic types of graphs you should know are bar graphs, line graphs, and circle graphs (or pie charts).

• Bar graphs convert the information in a chart into separate bars or columns. Some graphs list numbers along one edge and then list dates, places, people, or things (individual categories) along another edge. Always try to determine the relationship between the columns in a graph or chart.
• Line graphs convert data into points on a grid. These points are then connected to show a relationship among the items, dates, times, and so on. Notice the slopes of the lines that connect the points. These lines will show increases and decreases. The sharper the slope upward, the greater the increase. The sharper the slope downward, the sharper the decrease. Line graphs can show trends, or changes, in data over a period of time.
• A circle graph, or pie chart, shows the relationship between the whole circle (100%) and the various slices that represent portions of that 100%. The larger the slice, the higher the percentage.