Reading and Making Bar Graphs (Scale of 1) - First Grade Mathematics

While picture graphs use little drawings to represent data, bar graphs use solid, colorful bars! A bar graph is one of the most widely used graphs in science, business, and mathematics. In a bar graph, the length or height of each solid bar shows the quantity: longer bars mean bigger numbers, and shorter bars mean smaller numbers. Along the side of the bar graph is a numbered scale that lets you read the exact value instantly without having to count every unit! In this chapter, you will master reading and making bar graphs with a single-unit scale.

The Anatomy of a Bar Graph

A bar graph is constructed on a grid with a vertical axis and a horizontal axis.

Vertical Bar Graph: Favorite Season

Number of Votes
 6 |         [#]
 5 |         [#]
 4 |  [#]    [#]
 3 |  [#]    [#]
 2 |  [#]    [#]    [#]
 1 |  [#]    [#]    [#]    [#]
 0 +------+-------+------+------+
    Fall   Winter  Spring Summer

The Parts of a Bar Graph:

  1. Title: Explains the topic of the graph ("Favorite Season").
  2. Number Scale (Axis): A vertical number path running up the side (0, 1, 2, 3, 4, 5, 6).
  3. Category Labels: The names of the groups along the bottom (Fall, Winter, Spring, Summer).
  4. Colored Bars: Solid rectangular columns that rise to match the exact number of items.

How to Read a Bar Graph with a Scale of 1

Reading a bar graph is as easy as tracing with your finger!

The Finger Trace Method:
Step 1: Find the category you want to read (for example, "Fall").
Step 2: Follow the solid bar up to the very top edge.
Step 3: Slide your finger straight to the left to see which number it aligns with on the scale!

Reading the Seasons:

Fall: The bar stops at the line for 4. 4 votes! Winter: The bar stops at the line for 6. 6 votes! Spring: The bar stops at the line for 2. 2 votes! Summer: The bar stops at the line for 1. 1 vote!

Making Your Own Bar Graph

To draw a bar graph from data: Step 1: Draw your vertical and horizontal axes. Step 2: Number the scale starting at 0 at the bottom corner, going up by ones: 0, 1, 2, 3, 4, 5... Step 3: Label your categories along the bottom, leaving neat spaces between them. Step 4: For each category, shade in a bar from 0 straight up until it hits the correct number line!

Practice Exercises

Exercise 1: Describe the "Finger Trace Method" used to read the value of a bar on a bar graph.

Exercise 2: Look at the Favorite Season bar graph in this chapter. Which season received the greatest number of votes, and how many votes did it get?

Exercise 3: Which season received the fewest votes, and how many votes did it get?

Exercise 4: How many total votes were cast in the Favorite Season survey? Show the addition expression you use to add all the bars.

Solutions and Explanations

Solution to Exercise 1: Place your finger at the top edge of the category's bar, and slide your finger straight across to the number scale on the left. The number your finger touches is the exact value of that bar.

Solution to Exercise 2: Winter received the greatest number of votes, with a total of 6 votes.

Solution to Exercise 3: Summer received the fewest votes, with only 1 vote.

Solution to Exercise 4: Add the heights of all four bars: 4 (Fall) + 6 (Winter) + 2 (Spring) + 1 (Summer). 4 + 6 = 10, plus 2 = 12, plus 1 = 13. A total of 13 votes were cast.