Picture & bar graphs
Draw a picture graph and a bar graph (with single-unit scale) to represent a data set with up to four categories; solve put-together, take-apart, and compare problems using information presented in a bar graph
What a learner can do afterwards
- Draw a picture graph with a symbol representing one unit for each data point
- Draw a bar graph with labelled axes and a single-unit scale
- Read category counts from a bar graph, identify most or fewest, and find totals, differences and combined comparisons
1 · Read
You have recorded category counts before. Picture graphs use pictures and a key. Here, one picture represents one item or vote; other graphs can use other keys. Bars show category values. Find the requested category name, then read its bar's value on the number scale. Compare the values to find the largest count and the most items.
Zara's key says one heart picture represents one vote. Seven friends vote for hearts, so her picture graph needs seven heart pictures. Count each picture once. Its meaning comes from the stated key.
When drawing a bar graph, give it a title that describes the data. Name the categories and label the number axis with its unit. For a single-unit scale, equally spaced ticks go up by 1: 0, 1, 2, 3. Equal numerical changes need equal spaces. Skipping a printed label is not itself a scale error.
To find how many more votes cats have than dogs, read both bars: cats 8, dogs 6. Subtract the smaller count from the larger: 8 - 6 = 2. Cats have 2 more votes. Keep the vote unit with the result.
For a total, add every requested category. The pet counts are 8, 6 and 3, so 8 + 6 = 14, then 14 + 3 = 17 votes altogether. If a question names only two categories, add only those two. Check that you have not left out a requested category.
A combined comparison takes two steps. Dogs and fish together have 6 + 3 = 9 votes. Compare that combined count with cats' 8: 9 - 8 = 1. Dogs and fish together have 1 more vote than cats.
Read the key or scale. In this lesson, one picture means one unit. Label graphs clearly, add requested counts for totals, and subtract counts for differences.
The readings, questions and flashcards were written for this dataset. The linked videos are by Khan Academy.
2 · Watch
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Where this leads
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