Data Handling and Presentation

Collect data with tally marks, organise it in tables, and show it in pictographs and bar graphs with a key or scale.

Key ideas

• Tally marks are drawn in groups of five: four strokes and a fifth across them.
• A frequency table lists each item with how many times it occurs.
• A pictograph uses a picture for a fixed number of items; the key says how many each picture stands for.
• Part of a picture shows part of the number: half a symbol for half the key value.
• A bar graph uses bars of equal width; the length of each bar, read on the scale, shows the number.
• Choose a scale so that the longest bar fits on the page.

Remember

Watch out

• Forgetting to read the key, and counting each picture as 1.
• Making bars of different widths, or starting the scale above 0.
• Counting a group of tally marks as 4 instead of 5.

Worked example