A scaled picture graph uses a key where each symbol represents more than one unit — for example, each star = 2 votes. To find the total for a category, multiply the number of symbols by the scale value. If 5 stars represent votes for pizza and each star = 2, then 10 students voted for pizza. Scaled graphs are used when individual symbols would become too numerous.
Begin by asking students to draw a picture graph where each picture = 1, then show how many symbols it requires for large data sets. Introduce the key concept as a solution. Practice reading, interpreting, and drawing scaled picture graphs with a variety of scales (×2, ×5, ×10).
You already know how to read and make picture graphs where each picture stands for exactly one thing — one vote, one book, one student. That works well for small amounts. But what if you surveyed 60 students about their favorite sport? You'd need to draw 60 symbols. That's slow, crowded, and hard to read. The scale solves this problem by letting each symbol stand for more than one item.
The most important piece of any scaled picture graph is the key (sometimes called a legend). The key tells you what one symbol is worth — for example, "★ = 5 students." Without the key, the graph is unreadable. When you look at a graph and see 4 stars in the "soccer" row, the key is what tells you that means 4 × 5 = 20 students. This multiplication step is what distinguishes a scaled graph from a simple one-to-one graph.
Your skip-counting knowledge is the engine here. If each symbol equals 2, you read the graph by skip-counting by 2s: 2, 4, 6, 8... If each symbol equals 5, you skip-count by 5s: 5, 10, 15, 20... The scale you use is usually chosen to match what you can skip-count easily. That's why scales of 2, 5, and 10 are most common — you already have those sequences memorized.
When you create your own scaled picture graph, you have to make a key decision upfront: what should the scale be? If your largest category has 30 responses and you want no more than 10 symbols in a row, you'd choose a scale of at least 3. If all your counts are multiples of 5, a scale of 5 keeps everything clean. Designing the scale requires thinking about the data before you draw — another example of the "organize first, graph second" principle. A well-chosen scale makes a graph that's both accurate and easy to read.