Numbers and Operations Review

Learning Objective

Students will fluently add and subtract within 100 using strategies based on place value, properties of operations, and the relationship between addition and subtraction.

Learning Standards

• CCSS.MATH.CONTENT.2.NBT.B.5: Fluently add and subtract within 100 using strategies based on place value, properties of operations, and the relationship between addition and subtraction.
• CCSS.MATH.CONTENT.2.NBT.A.1: Understand that the three digits of a three-digit number represent amounts of hundreds, tens, and ones.
• CCSS.MATH.PRACTICE.MP1: Make sense of problems and persevere in solving them.
• CCSS.MATH.PRACTICE.MP7: Look for and make use of structure.

Key Vocabulary

• Place value
• Tens
• Ones
• Addition
• Subtraction
• Sum
• Difference
• Regrouping

---

Hook (Launch, Warm-Up) — 10 minutes

Activity: “Number Detective”

• Write several 2-digit and 3-digit numbers on the board (e.g., 47, 83, 129, 256).
• Have students turn and talk to identify the place value of each digit aloud.
• Use a “place value chart” visual and ask: “What is the value of this digit? How many tens/ones/hundreds?”
• Goal: Refresh place value understanding as a foundation for addition and subtraction.

---

Learn (Explore) — 20 minutes

Mini-lesson (I Do) — 10 minutes

• Using an anchor chart, model addition and subtraction within 100 using place value blocks or drawings.
• Demonstrate strategies such as breaking apart numbers by place value (e.g., 46 + 35 = 40 + 30 + 6 + 5) and using place value to regroup when subtracting.
• Emphasize the relationship between addition and subtraction with number sentences (e.g., 46 + 35 = 81 and 81 - 35 = 46).
• Show through annotated examples how to check work by reversing the operation.

Guided Practice (We Do) — 10 minutes

• Engage students with partner problem-solving with prepared number cards.
• Give pairs (or groups of 3) simple addition or subtraction problems using numbers up to 100.
• Circulate, prompting students to explain their reasoning and guide with questions like “How did you break the numbers apart?” and “Can you check your answer with subtraction?”
• Use small whiteboards so answers can be shown quickly for immediate feedback.

---

Independent Practice (You Do) — 30 minutes

• Distribute a worksheet with a mix of 15 addition and subtraction problems within 100. Problems will include:
  • Simple sums without regrouping.
  • Problems requiring regrouping (e.g., 47 + 38, 65 – 29).
  • Word problems incorporating addition and subtraction in real-life contexts (e.g., “Sally has 53 apples. She gives 27 to her friend. How many does she have left?”).
• Encourage students to use drawings or place value charts if needed.
• Provide math journals for students to explain their strategies or write a short sentence about how they solved one challenging problem.

---

Closing (Synthesis, Discuss) — 10 minutes

• Bring the class back together and facilitate a discussion on strategies used.
• Invite 2–3 students to share how they solved a problem and how addition and subtraction are connected.
• Reiterate the importance of place value in solving problems efficiently.
• End with a quick “Thumbs up / Thumbs down” self-assessment asking if they feel confident or if they have questions about today’s lesson.

---

Fluency Focus

• Daily practice with timed 1-minute addition and subtraction drills (e.g., flashcards or oral problems) starting from 10 problems to increase speed without sacrificing accuracy.
• Include games such as “Around the World” or “Math Bingo” to keep fluency practice engaging.

---

Differentiation

• For students needing extra support:

  • Provide manipulatives (base-ten blocks) to physically represent problems.
  • Offer one-on-one or small-group guided support focusing on place value concepts before independent work.
  • Use number lines for subtraction.

• For students ready to be challenged:

  • Present multi-step word problems involving addition and subtraction.
  • Introduce early concepts of three-digit addition/subtraction without regrouping.
  • Encourage them to explain their thinking in writing or drawing.

---

Assessment

• Formative: Observation during guided practice; math journals with explanations; student participation in discussion.
• Summative: Independent practice worksheet graded with a rubric focusing on accuracy and strategy explanations.
• Exit Ticket: On a half-sheet, students solve two problems — one addition and one subtraction within 100 — and explain the strategy used in one sentence.

---

This comprehensive, standards-aligned plan incorporates hands-on exploration, strategic modeling, and rigorous practice—all designed to build 2nd graders’ confidence and fluency in addition and subtraction within 100 while engaging multiple learning styles.