Finding the Difference Using the Crayon Box

Learning Resource Type

Learning Activity

Subject Area

Mathematics

Grade(s)

1

Overview

This learning activity will guide students through solving story problems. It will help the students unpack simple word problems with unknowns in all positions.  The students will use different strategies to solve problems. It will encourage the students to make sense of problems. This learning activity will engage the students so that they will feel confident in solving a variety of story problems.

This activity results from the ALEX Resource Development Summit.

Phase

During/Explore/Explain
Mathematics (2019) Grade(s): 1

MA19.1.1

Use addition and subtraction to solve word problems within 20 by using concrete objects, drawings, and equations with a symbol for the unknown number to represent the problem.

UP:MA19.1.1

Vocabulary

  • Change unknown
  • Put together
  • Take apart
  • Compare

Knowledge

Students know:
  • addition and subtraction strategies and models.
  • how to form an equation.

Skills

Students are able to:
  • represent quantities and operations (addition & subtraction) with concrete objects, pictorially, or symbolically.
  • Use informal and mathematical language to communicate the representations.
  • Accurately compute sums and differences.

Understanding

Students understand that:
  • addition is both putting together and adding to. subtraction is taking apart, taking from, and comparisons.
  • Mathematical problems can be solved using a variety of strategies. models, and representations.
  • variables in the form of blanks, boxes, or letters, represent unknown quantities when representing mathematical situations algebraically.
Mathematics (2019) Grade(s): 1

MA19.1.2

Solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20 by using concrete objects, drawings, or equations with a symbol for the unknown number to represent the problem.

UP:MA19.1.4

Vocabulary

  • Addend

Knowledge

Students know:
  • The relationship between addition and subtraction.
  • how to explain subtraction as an unknown addend.

Skills

Students are able to:
  • use symbols such as blanks, boxes, or letters to represent unknown quantities in equations.
  • Communicate the connections between subtraction and addition.
  • Use the inverse relationship between addition and subtraction to find differences.
  • Choose and apply addition and subtraction strategies to accurately determine sums and differences within 20.

Understanding

Students understand that:
  • addition and subtraction have an inverse relationship that can be used to solve problems.
Mathematics (2019) Grade(s): 1

MA19.1.8

Solve for the unknown whole number in various positions in an addition or subtraction equation, relating three whole numbers that would make it true.

UP:MA19.1.8

Vocabulary

  • Equation

    • Knowledge

    Students know:
    • Strategies for solving simple addition or subtraction equations with one unknown.

    Skills

    Students are able to:
    • solve simple addition and subtraction equations.
    • Justify and explain their thinking.

    Understanding

    Students understand that:
    • equalities contain expressions that name the same amount on each side of the equal sign, even with quantities unknown.

    Learning Objectives

    • The student will use addition and subtraction to solve problems within 20.
    • The student will determine the unknown whole number in addition and subtraction equations relating to three whole numbers (for example, 10-8=2).
    • The student will justify the reasonableness of his/her answer and explain his/her strategies.

    Activity Details

    1. Gather students on the floor to watch the video to review missing addends.
    2. Show students the following problem on the chart paper, asking them to read aloud with you.
      • Problem:  Maria has eight more crayons than Brian. Maria has 10 crayons. How many crayons does Brian have?
    3. Read the problem a second time.  
    4. This is the Extension of the problem for students that solve the first part easily: 
      • Ana has 4 crayons. If she puts her crayons with Brian and Maria's crayons, will they have enough to fill a box that holds 16 crayons?  How do you know?
    5. Ask students to restate the problem in their own words. Students will "unpack" the problem (give the information they know about the problem from reading it). This can be done by asking the following questions:  What information do you know from the problem? What information are you trying to find out?  
    6. Avoid encouraging students to use keywords as a solution strategy. In this particular problem, if a child were to pick out the word "more" and the two numbers, they might simply add and respond with the answer, 18. The discussion of what the problem is asking you to solve is key in building problem-solving techniques.
    7. Send students to workspaces to glue a personal copy of the problem in their journals or on a piece of paper.
    8. Have students solve the problem with pictures, manipulatives, words, and an equation.
    9. Record solutions in their journals or on the piece of paper.
    10. While students work, the teacher observes and asks questions, checking for understanding, and looking for students to share their strategies used to solve the problem.
    11. Bring students back together as a group for sharing. The teacher needs to allow students to do most of the talking and questioning, with the teacher offering support and clarification if needed.

    Assessment Strategies

    As the students work on the problem pose the following questions to check for understanding:

    • Tell me what you are thinking.
    • What does this part of your solution show?
    • Reread the problem for me. What is the problem asking you to find in it?
    • What tool did you decide to use for this problem? Why did you select it?
    • How can you represent this problem another way? Show me on your paper.

    After solving the problem, pose these questions:

    • Tell the group how you solved it?
    • What did you do first? Why?
    • What did you do next? Why?
    • What was your mathematical thinking for this problem?

    Variation Tips

    • Extension of the problem for students that solve the first part easily:  Ana has 4 crayons. If she puts her crayons with Brian and Maria's crayons, will they have enough to fill a box that holds 16 crayons? How do you know? 
    • Help struggling students create a picture representation of the problem, using labels for the students in the problem for the student in small chunks allowing the student to act out and test each part with materials.

    Background / Preparation

    • Review Critical Area 1 for First Grade to connect this lesson with key mathematical ideas of developing an understanding of addition and subtraction.
    • Prepare a written copy of the problem on chart paper.
    • Prepare a class set of the problem for individuals.
    • Prepare baskets of manipulative materials, which have been used in previous lessons, to assist the students in solving the problems.
    "Missing Addends: Finding a Missing Part for Kids" Video
    https://www.youtube.com/watch?v=Mvm0y1Qr_JQ

    Approved Date

    Owner (Author)

    kimhenderson
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