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A picture graph uses symbols to show data. Each symbol may represent 1 or more items (key shows the value). To read, count the symbols in each row; to create, decide on a symbol and draw rows to show data.
You already know that a picture graph uses symbols to represent data. Now you're working with something more powerful: a key that says each symbol stands for more than one item. Instead of drawing 14 stars for 14 votes, you could draw 7 stars and write "each ★ = 2 votes." The graph takes less space and is easier to scan — and the key gives readers what they need to recover the exact numbers.
Reading such a graph requires two steps: count the symbols in a row, then multiply by the key value. If the "cats" row has 5 paw prints and the key says each paw print = 3 students, then 5 × 3 = 15 students chose cats. If a row has 4 symbols and each symbol = 10, then 4 × 10 = 40. You're reversing the compression that was applied when the graph was made. This multiplication step is small but important — skipping it and just reporting the symbol count is one of the most common errors when reading picture graphs with scaled keys.
Creating a picture graph adds a decision you don't face when just reading one: what should the key value be? A good key keeps the number of symbols manageable — ideally between 2 and 10 per row — so the graph is readable at a glance. If the largest data value is 30, a key of "each symbol = 5" gives at most 6 symbols per row (clean and clear). A key of "each symbol = 1" would produce rows of 30 symbols (cluttered and hard to count). Choosing the right scale is a real design decision, and it's your first encounter with a skill that recurs throughout data work: representing information efficiently without losing accuracy.
When comparing rows, look for the row with the most symbols (most popular) and least symbols (least popular). You can also find differences: if one row has 6 symbols and another has 4, and the key is ×2, then one category has 12 and the other has 8 — a difference of 4. Always apply the key before comparing numbers, not after.