You can compare two different data sets on the same chart.
Accuracy.
Look at the diagram of my pointing finger: there!
the brake or cut
A line graph can have just one line, or several lines (often using differing colours for clarity). Using several lines make it easier to compare changes that have happened over a period of time.
The best way to make a graph is to draw straight axis lines with a ruler and space the points equally. Finally, plot the points. A cleaner, faster method, can be found by using a spreadsheet software, like excell.
The advantage is that you can compare multiple data sets in the same chart
You can compare two different data sets on the same chart.
By using multiple lines you can show multiple pieces of data; e.g. if you have a test for the heat of liquids, then you can show multiple different liquids on the same graph. Like water and oil, you can show the water as one line and the oil as another. Saving you the need to make more graphs and making data easier to compare.
Accuracy.
A bar graph is useful for showing the amount of the items yours comparing. This is great for a survey too.
Look at the diagram of my pointing finger: there!
Tables use lines and numbers instead of using bars words and numbers..... :) Also, you can't put your beer down on a bar graph :-)
Constant speed is shown on a graph using straight lines. The straight line indicates that there are no fluctuations with the speed.
the brake or cut
A line graph can have just one line, or several lines (often using differing colours for clarity). Using several lines make it easier to compare changes that have happened over a period of time.
A picture graph, instead of using bars or lines to measure quantities, uses pictures. http://www.schools.ash.org.au/revesby/images/pg.gif here's an example
It's easier to use than a single step.