Line Graph Maker

A line graph uses position twice: height shows the measured value, while left-to-right position shows where an observation belongs in a sequence. The second part is easy to overlook. Before drawing the graph, decide whether the first column contains categories, numbers, or dates.

• Categories: names such as Monday, Tuesday, and Wednesday usually receive equal spacing. Their order matters, but there is no numerical distance between the words.
• Numbers: measurements must use their real distance. On an axis containing 0, 1, and 10, the gap from 1 to 10 must be nine times the gap from 0 to 1. Even spacing would invent a pattern that the data does not contain.
• Dates: dates also need real spacing. A measurement taken one day after the first belongs much closer than one taken three weeks later, even if those observations occupy neighbouring spreadsheet rows.

The automatic setting checks every used horizontal value. If every value is a number, it uses number spacing. If every value is a recognised date, it uses elapsed time. Otherwise it treats the labels as categories. Choose a mode yourself when a set of numeric-looking labels, such as classroom codes 1, 2, and 10, should remain equally spaced categories.

A classroom graph is often viewed smaller than it appeared on screen. It may be pasted into a worksheet, printed in greyscale, or copied several times. A readable graph therefore needs more than attractive colours.

• Name both axes and include units. Reading Fluency Progress is a useful title only when the vertical axis also says Words correct per minute and the horizontal axis says Month.
• Keep the legend short. Group A and Group B remain readable when the graph is reduced. Put detailed explanations in the worksheet text instead of a long series name.
• Use markers and line patterns. This tool assigns both automatically, so two series remain distinguishable after black-and-white printing or for a reader who cannot separate the colours.
• Limit crowded labels. With many categories, the graph rotates and samples horizontal labels. Value labels are also sampled on a dense graph. The data is still present in the lines and editable table.
• Choose SVG for document work. SVG text and lines stay sharp when resized. PNG is useful for software that accepts only bitmap images, while Print produces an ink-efficient landscape page sized for Letter or A4.

A quick final check is to print in greyscale at the size students will receive. If the series, units, and gaps remain obvious without zooming, the graph is ready for the worksheet.