Bar Graphs

When there are a lot of things, drawing a picture for each one takes too long.

A bar does the same job

The height of the bar tells you the number. Read it against the scale.

Same rules apply

All the bars start on the same line, and the scale steps by the same amount each time.

A bar instead of a row of pictures

A bar graph replaces the row of pictures with a solid bar whose length shows the count. You read the count off the scale along the side or bottom. Bars are quicker to draw than pictures and handle large numbers without needing hundreds of symbols.

Read the scale carefully

The scale might go up in 1s, 2s, 5s or 10s. If it goes up in 2s, a bar reaching the fourth line means 8, not 4. Checking the scale before reading any bar is the single most important habit in reading graphs.

The parts every graph needs

A graph needs a title saying what it shows, labels on both axes, and a scale with even spacing. Without those it is just coloured rectangles. When you draw your own, add all three before you shade a single bar.