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# Lesson 2: Charting and Graphing Sales

• Lesson Title: Charting and Graphing Sales
• Lesson Length: Approximately 2 days
• NCTM Standard: Algebra Standard

#### Learning Objectives

1. The student will analyze and represent weekly sales figures using tables, bar graphs, and pie charts.
2. The student will draw conclusions using bar graphs and pie charts.

#### Connection to Bloom’s Taxonomy

• Comprehension
• Application
• Analysis
• Synthesis

#### Lesson Materials

• Calculators
• Crayons or Colored Pencils
• The Geddes School Supply Catalog or web site
• Index Cards
• Pencils
• Worksheets for lesson plan 2 (see sidebar)

## Making Connections

Explain to students that each day at school they have the option of buying or bringing a lunch from home. Survey the class to find out how many students will buy or eat a lunch from home on the day of the lesson. Have students brainstorm how this information or data can be represented other than merely stating the facts in words or with simple numbers. Can they think of any visual tools that can be used to show this information?

Explain to students that your survey tells you that eight students purchased lunch today and fourteen brought a lunch. State that visualizing this information or data would be more interesting, and at times easier to understand rather than simply saying it. Tables, pie charts, and bar graphs are all useful tools for visually representing data. Often times the more data you have, the easier it is to understand using visual tools.

Discuss the following questions:

1. Where have you seen pie charts and graphs?
2. What type of information would be better represented in a pie chart or graph?
3. What are some of the benefits of representing data in a visual format?

## Exploring and Learning

1. In the Making Connections section, a survey was taken to compare the number of students who purchased lunch verses those who pack a lunch. Show a simple bar graph that visually represents the two data numbers collected during the survey. Explain that a graph can represent more than just two data points.
2. Ask students to categorize their main lunch choices into one of the following options (or any other categories that might be appropriate): sandwich, salad, soup, hot meal, fruit, or yogurt. Write the information on the board. In a class of 22 students, perhaps:
• 8 selected the hot meal,
• 2 ate yogurt
3. Ask students to think about how this information could be presented visually. Using class specific information gathered from student input or data from the example above, demonstrate how the information could be presented as a bar graph and pie chart. Guide students through the process by using the Lunch Survey Guided Practice Worksheet (PDF). The guided practice worksheet can be used as a transparency.

Note: The bar graph and pie chart can be created by hand or by using any graphing software available to students. Explain that a bar graph is constructed using the raw data numbers collected. However, the pie chart uses percentages created from the data. Remind students that a percent is a ratio whose second term is 100. For example, the ratio of 30 : 100 is 30%. More simply, percent means parts per hundred. Follow these 5 simple steps to finding the percentage in the lunch survey.

Finding the percentage for the category ‘Sandwich’:

• Step 1: How many total students completed the survey? (22)
• Step 2: How many students ate a Sandwich? (5)
• Step 3: Write the result as a fraction? (5/22)
• Step 4: Solve the fraction using a calculator. (.227)
• Step 5: Change the fraction to a percent. (.227 x 100 = 22.7 or 23)
4. Using the completed Lunch Survey worksheet, ask students the following questions:
• Look at the bar graph and pie chart. Which lunch choice was the most popular today? (hot meal)
• Which choice was the second most popular? (sandwich)
• Which choice was the least popular today? (soup)
• Do you find one visual tool easier to analyze than the other?
5. The school cafeteria manager might be very interested in analyzing the lunches students prefer or what lunches they purchase on a daily or weekly basis. Have students brainstorm reasons why this information might be useful. Possible answers might include the following:
• a monthly menu can be planned based on student preferences
• the correct ingredients can be purchased in advance
• the right amount of ingredients can be purchased in advance
• time needed to prepare the meals can be determined
6. Present students with the following scenario:

RG and Hannie are working at the Raymond Geddes Elementary School Store. This week they are offering eleven items for sale. They want to analyze their weekly sales by major product categories: pens, erasers, pencils, mechanical pencils and sharpeners.

Can you help RG and Hannie create a table, bar graph, and pie chart to represent their weekly sales information?

What product categories generated the most total sales and the least total sales in dollars?

7. To help complete the scenario, divide students into pairs and provide them with a copy of the Geddes Weekly Sales Worksheet (PDF). The worksheet provides quantity and retail price information. It is also color coded to help student’s group information into product categories. If time is limited, calculate and complete the total sale column of the worksheet for students prior to distributing the handout. Provide students with the following instructions:
• Step 1: Using calculators, calculate the total sale for each item using the quantity provided. Record the amounts in the column labeled “total sale.” Calculate the total sales amount for the entire week and record that figure in the “Total Weekly Sales” box.
• Step 2: Tally by product category and complete the table. What were the weekly total sales figures for pens, erasers, pencils, and mechanical pencils? Calculate sales percentages for each product category. For example, pens represent what percentage of the week’s total sales?
• Step 3: Create a bar graph showing the total sales for each product category.
• Step 4: Create a pie chart using percentages generated in Step 2.
• Note: If you have a school store, change the quantity sold and the retail price to meet the needs of your individual sale and store. Or, if you are using the Geddes School Store Kit, use this opportunity to run your school store and record your own quantities sold. There are 11 items of the kit used in the exercise, however, the same exercise could be done using the complete kit.
8. Conclusion: Answer the following two questions:
• Which product category had the most total sales at RG and Hannie’s school store? (pens)
• Which product category had the least total sales this week? (grips)

## Extended Learning and Practice

1. Provide students with a scenario that the school store manager would like more detailed information about the sale at the school store. Create a chart that provides detail at the product level for each individual item. There are eleven product items in total. Find out which individual product item had the most total sales and the least total sales.
2. Create a pie chart to analyze individual categories of pens, pencils, erasers, or mechanical pencils. For example, which type of pen had the highest total sales for the week: the Study Buddy Pen, 6 Color Pen, or the Twister Pen?
3. This lesson analyzed sales in dollars. Review the sales information again, but analyze the quantities sold instead of dollar amount.
• How many items were sold in total?” (168 items)
• What does the breakdown look like by product category?
1. Pens = 55 or 20% of total items
2. Erasers = 72 or 27% of total items
3. Pencils = 72 or 27% of total items
4. Mechanical Pencils = 69 or 26% of total items
4. Visit National Center for Education Statistics (NCES) Kids Zone—Create a Graph for additional graphing activities

## Assessment

The lesson objectives can be assessed by evaluating students’ abilities to:

1. Use the Geddes Weekly Sales Worksheet Key (PDF) to assess each team’s ability to analyze and represent weekly sales figures using tables, bar graphs, and pie charts.
2. Use the Assessment of Student Progress (PDF) to assess students’ overall abilities to meet the lessons learning objectives which include creating visual representations of data and drawing conclusions from tables, bar graphs, and pie charts.

## Closure

Provide each student with an index card and have them answer the following questions on one side of the index card:

1. What are two new things that you have learned?