The sequence of major events related to a topic can be written on a time line. Time lines can have various scales. One inch may represent one second, one year or a million years. The appropriate scale should be determined for the number of essential events available. Several time lines with different scales may be necessary if material included moves from prehistoric times to the present. The scale must remain the same on any one time line in order to give an accurate portrayal of the events.

A time line can be drawn in a vertical or horizontal fashion.

Sometimes it is helpful to draw several columns next to the dates. A different aspect of a topic can be shown in each column.