Subject

Mathematics

Learning Objective

Students will be able to represent and solve addition and subtraction story problems using equations, tape diagrams, and number lines with accuracy and confidence.

Learning Standards

• 2.OA.A.1: Use addition and subtraction within 100 to solve one- and two-step word problems.
• 2.MD.B.6: Represent whole numbers as lengths from 0 on a number line diagram with equally spaced points.
• 2.NBT.B.5: Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.

Key Vocabulary

• Addition
• Subtraction
• Equation
• Tape diagram
• Number line
• Sum
• Difference
• Unknown (variable)

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Lesson Sequence (90 minutes)

Hook (Launch, Warm-Up) — 10 minutes

Activity: Story Problem Brainstorm Circle

• Gather students in a circle.
• Tell a brief story: “There are 7 apples on the table. I bring 5 more apples. How many apples are there now?”
• Have students express the situation in their own words and act it out with fingers or small objects.
• Prompt students to share different ways to think about the story problem.

Purpose: Activate prior knowledge of addition and subtraction through engaging story context and oral sharing.

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Learn (Explore)

Mini-Lesson (I Do) — 15 minutes

Topic: Representing Story Problems with Equations, Tape Diagrams, and Number Lines

• Present a story problem on the board, e.g., “Sarah has 12 balloons. She gives 5 to her friend. How many balloons does Sarah have left?”
• Model step-by-step:
  • Write the equation: 12 - 5 = __
  • Draw a tape diagram: one bar divided into two parts labeled 5 and unknown.
  • Draw a number line from 0 to 12, show starting at 12, then subtracting 5 steps left to find the answer.
• Emphasize vocabulary: sum, difference, equation, tape diagram.
• Think aloud to explain the reasoning behind each representation.

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Guided Practice (We Do) — 20 minutes

Activity: Small Group Work with Manipulatives and Visuals

• Divide class into pairs or groups of three with 4-5 groups total. Provide each group with:
  • Strips of paper to create tape diagrams.
  • Number lines on laminated sheets where they can mark with dry-erase markers.
  • Counters or cubes.
• Give each group a different two-step story problem involving addition and subtraction (within 100). Example:

  “James had 30 marbles. He gave 7 to his sister and then found 10 more under his bed. How many marbles does he have now?”

• Circulate and support students as they represent problems with equations, draw tape diagrams, and mark number lines together.
• Ask guiding questions: "What does this part of the tape diagram show?" "How do we show the subtraction on the number line?"

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Independent Practice (You Do) — 25 minutes

Task: Individual Story Problem Journals

• Provide each student with a Story Problem Journal page including:
  1. A written story problem.
  2. Space to write an equation.
  3. Space to draw a tape diagram.
  4. Space to draw a number line.
• Include 3 problems increasing in difficulty (one- and two-step).
• Encourage students to use color pencils to organize their work (e.g., blue for subtraction, green for addition).
• Teachers circulate to support students needing help and to check for understanding.

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Closing (Synthesis, Discuss) — 10 minutes

• Gather students back as a whole group.
• Have 3-4 students share one of their story problems and explain how they solved it using an equation, tape diagram, or number line.
• Discuss how different methods help us understand the problem better.
• Reinforce key vocabulary one last time.
• Celebrate effort with verbal praise or a quick class applause line.

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Fluency Focus

• Daily quick oral math facts review (addition and subtraction within 20).
• Number line hopping game during recess to reinforce jump counting forwards and backwards.
• Timed flashcard rounds adapted for individual student levels, two rounds per student per week.

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Differentiation

• For Students Needing Support:
  • Use smaller numbers (< 20) with more visual aids.
  • Work in pairs with stronger peers.
  • Provide pre-drawn partially completed tape diagrams or number lines.
• For Advanced Students:
  • Introduce three-step story problems.
  • Use missing addend or missing subtrahend problems (e.g., __ - 5 = 7).
  • Challenge to write their own story problems and representations.

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Assessment

• Formative: Teacher observations during guided and independent practice using a checklist for correct use of equations, tape diagrams, and number lines.
• Cool Down: Exit ticket - one quick story problem where students write the equation and draw a number line.
• Section Checkpoint: End-of-week quiz involving 3 story problems requiring multiple representations, scored with rubric on accuracy and completeness.

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Materials Needed

• Whiteboard and markers
• Paper strips for tape diagrams
• Laminated number line sheets + dry erase markers
• Counters/cubes
• Story Problem Journals (prepared worksheets)
• Colored pencils or crayons

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This lesson plan provides a well-paced, multi-modal approach that support 2nd graders in mastering addition and subtraction story problems confidently while meeting and exceeding Common Core standards.