Read a Bar Graph

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Objective

SWBAT analyze and compare data shown in a bar graph

Big Idea

In this lesson, students will be introduced to bar graphs and the importance of labeling the parts of the graph.

Activating Strategy

10 minutes

I started off the lesson by showing children a red 3-cube train and a blue 5-cube train, with the cube trains aligned at one end.

  • Which is longer? Which is shorter?

To check their answers, I have children count the number of cubes in each cube train. I repeat this several times, comparing two cube trains of different lengths.

I then explain to children that in today’s lesson they will read graphs by comparing lengths of colored bars.

In the standard MD.C.4, students will need to not only read the bar graph, they will also have to be able to answer questions about which data point has more or less, and compare them to each other. A bar graph uses shaded bars to represent data, and children need to look at the length of the bar to determine the number.  In order to analyze and interpret data on a bar graph, I have found that it is important for children to be able to correctly label the parts of a graph.

  • Each bar graph needs to have a title reflecting the data that has been collected.
  • Each axis of the bar graph needs to be labeled. After identifying the categories of data, each category should be labeled with a word or a picture. The number of items needs to be labeled on the other axis, starting with 0.

By ensuring that their bar graphs will have the correct title and labels, students will also be meeting Mathematical Practice 6, attending to precision.  This practice is important in that students will be labeling their graph and axis to clarify the quantities in their graph.

Teaching Strategies

15 minutes

I read the following problem aloud to the class.  (The picture graph is located in the PowerPoint Read a Bar Graph.ppt found in the resources section.)

Emma’s class made this picture graph. What question could Emma’s class answer using the graph?

  • What do you need to write? a question about the graph
  • What information does the bar graph show? (The graph shows the numbers of children wearing laces or no laces on their shoes.)
  • What is one thing you learned from this graph? (There are more children wearing laces than no laces on their shoes in Emma’s class.)

I then have students write down a question about the bar graph.  After writing their questions, I have children exchange papers with a classmate. I have the classmate answer the question, and then have the child checks the answer.

Looking at the bar graph on the second slide, I guide children through the model with the following questions.

  • How can you tell the length of the bar for markers? (I find the line at the end of the red bar and follow it down to the number 5.)
  • What does the red bar tell you?  (It tells how many children chose markers as their favorite art tool.)
  • What clues help you write a title for the bar graph?  (I use the labels for the rows and numbers.) 

In this standard, MD.C.4, some students may have difficulty finding the value for a given bar in a bar graph.  To help with this, I like to teach my students to touch the end of the bar and follow the line to determine the number that the bar is representing.  This helps them make the connection that the end of the bar represents the data point.

Independent Practice

30 minutes

For the independent practice portion of this lesson, I have students complete the Read a Bar Graph_worksheet.

Here is a video of one of my students doing the independent practice portion of this lesson:

Closing/Summarizing

5 minutes

To close out the lesson, I have students draw a bar graph in their math journal, using the following information:

Graph title:  How to Tie Shoes

7 students know how to tie their shoes

3 students do not know how to tie their shoes