Understanding Scaled Picture Graphs and Bar Graphs

When we have a lot of data to show, drawing a single picture or coloring a single box for every single item can take up too much space. That is why we use scaled graphs. A scale means that one picture or one grid line stands for more than one item.

Scaled Picture Graphs

A picture graph (or pictograph) uses pictures to represent data. In a scaled picture graph, each picture stands for a specific number. You must always check the key at the bottom of the graph to see what the scale is.

Example: Imagine a graph showing how many books students read. The key says: 1 Book Picture = 5 Books

If Sarah has 4 book pictures next to her name, how many books did she read? Since each picture is worth 5 books, you multiply the number of pictures by the scale: $4 \times 5 = 20$ Sarah read 20 books!

Tip: Sometimes you might see a half picture. If 1 whole picture = 10 items, then a half picture equals exactly half of that amount, which is 5 items.

Scaled Bar Graphs

A bar graph uses rectangles (bars) to show data. In a scaled bar graph, the numbers along the side (the scale) do not count by 1s. They might skip count by 2s, 5s, 10s, or even 100s!

Example: You are looking at a bar graph of favorite school subjects. The numbers on the left side go: $0, 10, 20, 30, 40$.

If the bar for "Math" goes all the way up to the line for 30, it means 30 students chose Math.

What if a bar stops exactly halfway between 10 and 20? Halfway between 10 and 20 is 15. So, that bar represents 15 students.

Steps to Read a Scaled Graph

1. Find the Key or Scale: Always look for the key in a picture graph, or check the numbers on the side of a bar graph.
2. Skip Count or Multiply: If the scale is 2, count the pictures or grid boxes by 2s ($2, 4, 6, 8...$). You can also multiply the number of pictures by the scale value.
3. Watch for In-Between Values: Pay close attention to half-pictures or bars that end halfway between two lines on the scale.