what's on sale? lesson plan

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  • Lesson Title: What’s on Sale at the School Store?
  • Grade Band: 3-5
  • Lesson Length: Approximately 2 days
  • NCTM Standard: Number and Operations Standard

Learning Objectives

  1. The student will calculate sale prices based on 10%, 25%, 50%, and 75% price reductions.
  2. The student will demonstrate proficiency using a calculator to calculate new sale prices.
  3. The student will recognize that percentages can also be stated as decimals and fractions.

Connection to Bloom’s Taxonomy

  • Application
  • Analysis
  • Comprehension

Lesson Materials

  • Calculators
  • Crayons or Colored Pencils
  • The Geddes School Supply Catalog or web site
  • Index Cards
  • Newspaper
  • Worksheets for lesson plan 1 (see sidebar)

Making Connections

When you enter a department store or supermarket, what do you notice?

Have students brainstorm what they see when they enter a store. The list could include the following: aisles, merchandise, shopping carts, shelves, and cash registers. Explain to the students that one of the most important components of a store is a price tag. The price tag lists the retail or selling price of the item. Every item that is to be sold has a retail or selling price.

Is the price tag always the final price the customer will pay?

Explain to students that there are many items for sale in a store and often there are items on sale. Sometimes a store may offer a discount to buyers. When an item is on sale, the retail or selling price is lowered by a certain percentage or by a fixed dollar amount. For example, during a sale, a book’s selling price might be lowered by 25% or be reduced by a fixed dollar amount such as $2.00 off.

Discuss the following questions:

  1. Have you ever purchased something on sale?
  2. What does it mean to buy something on sale?

Exploring and Learning

  1. Explain to students that price reductions can occur not only on items found in a department store or supermarket, but also on any item a customer might purchase. Cars, houses, and even services (for example, lawn care, a hair cut, house painting, etc.) can be offered at a reduced price.
  2. Divide the class into groups (each containing 3-4 students). Assign the following roles to each group:
    • Liaison: act as liaison between group and teacher. Responsible for asking questions the team may have during this activity.
    • Recorder: responsible for circling sale advertisements, clipping ads, and/or recording sale information
    • Speaker: present group information at the end of the activity
  3. Provide each group with a newspaper. Have each group search through the newspaper to identify various ways merchandise and services are discounted. For example, some advertisements may state a specific percent off the retail price, a dollar amount off the retail price, a quantity discount, a coupon savings, or some other special offer. Refer to the Discount Samples Worksheet (PDF) for examples that can be viewed as a transparency.
  4. Gather the class together and ask each group speaker to share one or two price reduction examples from the newspaper.
  5. Explain to students that store merchandise on sale may be discounted commonly by 10%, 25%, 50%, or even 75%. These percentages can also be represented as decimals and fractions. For example, 10% is the same as $0.10 or 1/10; 25% is the same as $0.25 or 1/4; 50% is the same as $0.50 or 1/2; and 75% is the same as $0.75 or 3/4.
  6. Ask students to think about how the sale price is calculated when you know the original retail or selling price and the % discount. Guide students through the process of problem solving by using the Calculate Sale Price Guided Practice (PDF) as a transparency.
  7. Although most students are not making significant purchases on their own without the assistance of an adult, they might be allowed to shop in the school store. Present students with the following scenario:

    RG and Hannie are working at the Raymond Geddes Elementary Bookstore. Today they are going to learn how to calculate sale prices based on 10%, 25%, 50%, and 75% discounts. Sniffer, their dog, already knows how to calculate the new prices.

    Can you help RG and Hannie calculate the new sale prices?

  8. Divide students into pairs to complete the Items on Sale Worksheet (PDF). Provide each pair with a hard copy of the Raymond Geddes and Company School Supply Catalog, or on-line access to the Raymond Geddes website at http://www.raymondgeddes.com//. You may want to divide the class up into sections and assign each group with 2-4 of the 20 items listed on the worksheet. This will save time and still allows students to have the experience of looking up product items in a catalog or on-line.
  9. Provide students with the following instructions:
    • Using the hardcopy catalog or on-line catalog, locate each item’s retail price and fill in the retail column of the worksheet
    • If using the on-line catalog, simply enter the item number to locate the item and retail price.
    • Using calculators and the discount percentage provided, calculate each item’s new sale price. Convert the percentage to a decimal (or fraction) to complete the calculations. Round where needed.

Extended Learning and Practice

  1. Visit Figure This! Math Challenges for Families (National Council of Teachers of Mathematics) for additional percentage related activities and problems.
  2. Have students to look up the cost (provided in parentheses in the Raymond Geddes catalog) of several items. Explain that the cost is the amount the school store pays to purchase the items to be sold at the school store. This is not the retail price. Would the item still make a profit using the new sale price? For example, the Twist ‘N’ Sweep Eraser has a retail price of 75¢ and a cost of 54¢. The profit is 21¢. However, with a 10% discount, the retail price is reduced by 7¢ to 68¢. A profit still exists, but is also reduced by 7¢ from the original 21¢ to 14¢.


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

  1. Use the Items on Sale Key (PDF) to assess each team’s ability to calculate sale prices using 10%, 25%, 50%, and 75% price reductions.
  2. Use the Assessment of Student Progress (PDF) to assess students’ overall abilities to meet the lessons learning objectives which include, calculating sale prices based on specific price reductions, using a calculator to compute the sale prices, and recognizing that percentages can be represented also as decimals and fractions.


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

  1. What are two new things that you have learned?
  2. What else would you like to learn about this topic?

On the back side of the index card, instruct the students to draw a picture of something they learned about during this lesson. The index cards can be hole punched and held together with a simple shower curtain ring.

Teaching Strategies

  • Brainstorming
  • Cooperative Learning
  • Guided Practice
  • Paired Learning

Literary Connection

Math Man by Teri Daniels is a humorous children’s book that provides a story line with real world math applications.

Math Man is actually Garth, a stock boy at the Mighty Mart supermarket. Math Man takes Mrs. Gourd’s class on a tour of the supermarket and provides them with real world math scenarios that use addition, subtraction, multiplication and other math concepts.

Recommended audience is grades K-5.

Word Origins

Percent is from the Latin word per centum which was used as an abbreviation and means by the hundred. It was later abbreviated per cent. Using the period punctuation, but eventually the two words came together as one and the period was dropped. Have students create sentences using the word percent.

Hannie saved a percent of her allowance each week.

Vocabulary List

  • Merchandise: Items offered for sale in a store
  • Retail price: The price an item is sold for in a store (same as selling price)
  • Selling price: The price an item is sold for in a store (same as retail price)
  • Discount: The amount the retail price or selling price is reduced
  • Customer: Someone who pays for goods and/or services
  • Cost: The amount a store pays to purchase an item for inventory