Pick the right chart

The idea

Bar charts compare groups, line graphs show change over time, and pie charts show parts of a whole.

Which chart would you draw?

Meera measured her bean plant every week for eight weeks. Which chart would show best how it grew?

• A bar chart, with one bar for each week
• A line graph joining the weekly heights
• A pie chart of the eight heights

Match the question to the chart

Each card is a question that someone wants to answer with a chart. Tap a group. Read the reason, then press Next card.

The question picks the chart

Each card asked a different kind of question. "Which is biggest?" pointed to bars. "How did it change?" pointed to a line. "What share?" pointed to a pie.

Back to Meera's bean plant. She asked how it grew week by week, so a line graph suits it best. Watch for tricky words: months appeared in the birth-month card, but nothing changed over time, so bars fitted.

Bar charts compare groups, line graphs show change over time, and pie charts show parts of a whole.

Notes

Bar charts compare groups, line graphs show change over time, and pie charts show parts of a whole.

Ask yourself first: am I comparing groups, following change over time, or splitting a whole?

Check yourself

Kabir's school library has 400 books: story books, science books and comics. He wants to show how the 400 are shared among the three kinds. Which chart fits best?

Anil records his town's rainfall every year for ten years. He wants to see if it is going up or down. Which chart fits best?

Which of these questions is best answered with a bar chart?

• A line graph of the three kinds of book. A line graph follows change over time. His question is about how one total is split, not about time.
• A pie chart of the three kinds of book — correct. Yes. The three kinds together make the whole 400 books, and each slice shows its share.
• A bar chart of the three kinds of book. Bars could show each count, but they do not show the three kinds filling one whole. For a split, a pie is clearer.
• A pie chart of the ten years of rain. Ten years of rainfall do not add up to one whole that splits into parts.
• A bar chart with one bar for each year. Bars can show each year. But a line joins the years in order, so the up or down is easier to see.
• A line graph that joins the ten years — correct. Yes. The question is about change over time, and a line makes the direction clear at a glance.
• Which of the five classes collected the most old newspapers this month? — correct. Yes. Five classes are five groups, and the tallest bar shows the winner.
• How did the newspapers collected change over the whole term?. That asks about change over time, so a line graph suits it better.
• What share of all the newspapers did each class collect?. A share of a whole is the job of a pie chart.