Grade 2 Mathematics: Addition and Subtraction to 100 Using Place Value Strategies – Week 2-3 Term 4

1. Place Value

The value of a digit based on its position in a number. In the number 47, the 4 is in the tens place (worth 40) and the 7 is in the ones place (worth 7).

2. Split Strategy

A method of adding or subtracting by separating numbers into tens and ones, calculating each part separately, then combining the results. For example: 34 + 25 = (30 + 20) + (4 + 5) = 50 + 9 = 59

3. Decompose

To break apart a number into smaller parts. For example, 46 can be decomposed into 40 and 6, or 30 and 16, or other combinations.

4. Regroup

To exchange 10 ones for 1 ten, or 1 ten for 10 ones when adding or subtracting. Also called “carrying” or “borrowing” in traditional algorithms.

5. Number Bond

A visual model showing the relationship between a whole number and its parts. Helps learners understand how numbers can be combined or separated.

Mental Mathematics Warm-Up (5 minutes):

Quick-fire mental math questions to activate prior knowledge:
• Count in tens from 23 to 93
• What is 10 more than 34? 10 less than 67?
• Quick addition: 20 + 30 = ? 40 + 50 = ?
• Number bonds: 7 + ? = 10; 4 + ? = 10
• “Show me 4 tens and 3 ones with your fingers!”

Hook Activity (5 minutes):

The Sweet Shop Problem: Display a simple word problem on the board: “Thabo has 34 marbles. His friend gives him 23 more. How many marbles does Thabo have now?”

Ask learners: “How could we solve this problem? Can we just count on our fingers? That would take too long! Today we’re going to learn clever strategies that make adding and subtracting big numbers much easier!”

Briefly discuss with a partner what strategies they might try. Gather a few ideas to revisit later.

Direct Instruction (15 minutes):

Teaching the Split Strategy for Addition:

1. Concrete Stage: Use base-ten blocks under a document camera or on the board to solve 34 + 23:
   • Show 34 using 3 tens rods and 4 ones cubes
   • Show 23 using 2 tens rods and 3 ones cubes
   • Group all the tens together: 3 tens + 2 tens = 5 tens (50)
   • Group all the ones together: 4 ones + 3 ones = 7 ones (7)
   • Combine: 50 + 7 = 57
2. Representational Stage: Draw the problem using simple tens (sticks/lines) and ones (dots/circles):
   • Write: 34 + 23 = (30 + 20) + (4 + 3)
   • Draw 3 sticks + 2 sticks = 5 sticks (50)
   • Draw 4 dots + 3 dots = 7 dots (7)
   • Combine: 50 + 7 = 57
3. Think Aloud: “I’m going to split these numbers into tens and ones because it’s easier to add them separately. First, I add the tens: 30 + 20 = 50. Then I add the ones: 4 + 3 = 7. Finally, I put them together: 50 + 7 = 57!”

Teaching the Split Strategy for Subtraction:

1. Model 57 – 23 using blocks (without regrouping first):
   • Show 57 as 5 tens and 7 ones
   • Subtract 2 tens: 5 tens – 2 tens = 3 tens (30)
   • Subtract 3 ones: 7 ones – 3 ones = 4 ones (4)
   • Combine: 30 + 4 = 34
2. Record the strategy in expanded form: 57 – 23 = (50 – 20) + (7 – 3) = 30 + 4 = 34

Guided Practice (15 minutes):

Working Together:

• Activity 1: Solve 45 + 32 together as a class. Have learners use their own base-ten blocks or draw representations at their desks while you model on the board. Encourage learners to explain each step aloud using proper mathematical language.
• Activity 2: Try 68 – 24 together, following the same process. Ask guiding questions:
  • “What do we do first?”
  • “How many tens do we have left?”
  • “How many ones are left?”
  • “What is our final answer?”
• Activity 3: Pair Work – Give learners 2-3 problems to solve with a partner using blocks or drawings:
  • 26 + 41 = ?
  • 73 – 52 = ?
  • 54 + 35 = ?

  Circulate to observe, assist, and ask probing questions. Encourage learners to explain their thinking to their partners.

Independent Practice (10 minutes):

Individual Work:

• Distribute worksheets with 6-8 problems requiring addition and subtraction using the split strategy
• Problems should include both calculation exercises and simple word problems
• Encourage learners to draw tens and ones if they need help visualizing
• Sample problems:
  • 43 + 25 = ?
  • 76 – 34 = ?
  • “Nomsa has 52 beads. She buys 37 more. How many beads does she have now?”
  • “There were 84 learners at school. 42 went home early. How many learners are still at school?”

Consolidation Activity (7 minutes):

Quick Share and Review:

• Invite 2-3 learners to share their solutions on the board, explaining their thinking step-by-step
• Return to the marble problem from the hook: “Now let’s solve Thabo’s marble problem using our new strategy!”
• Solve 34 + 23 together using the split strategy, celebrating how much easier it is than counting
• Quick review questions:
  • “What does ‘split strategy’ mean?”
  • “Why do we separate tens and ones?”
  • “When might you use this strategy at home or when shopping?”

Exit Ticket (3 minutes):

Each learner completes a quick problem on a mini whiteboard or paper slip:
Problem: 51 + 36 = ?
Instruction: “Show your work using the split strategy. Draw tens and ones if it helps!”

Collect exit tickets to assess understanding and plan follow-up lessons.

📝 Formative Assessment

• Observe learners during guided practice – Are they correctly separating tens and ones?
• Listen to partner conversations – Can they explain their reasoning?
• Check independent work for common errors or misconceptions
• Monitor use of concrete materials – Are learners building models correctly?
• Ask probing questions during circulation: “How did you know to do that?” “Can you show me another way?”

📋 Summative Assessment

• Exit ticket completion and accuracy
• Independent worksheet performance (aim for 75% accuracy or higher)
• Ability to solve contextual word problems correctly
• Quality of explanations when sharing solutions

🤝 For learners who need support:

• Provide base-ten blocks or counters for all activities (keep it concrete longer)
• Use smaller numbers initially (numbers to 50) until confidence builds
• Create a visual anchor chart showing the split strategy steps they can reference
• Pair with a peer buddy who can model the strategy
• Use problems without regrouping initially
• Provide sentence frames: “First I split ___ into ___ tens and ___ ones…”
• Give one-on-one support during independent practice
• Use larger, clearer worksheets with fewer problems

🚀 For advanced learners:

• Challenge with 3-digit addition and subtraction (extending to 200 or beyond)
• Introduce problems that require regrouping
• Ask them to create their own word problems for classmates to solve
• Encourage them to find multiple strategies to solve the same problem
• Give multi-step problems: “Sipho had 45 marbles. He got 32 more, then gave 21 away. How many does he have now?”
• Ask them to teach the strategy to a struggling classmate
• Challenge: “Can you solve this problem mentally without writing anything down?”

♿ For learners with barriers to learning:

• Use large manipulatives that are easy to handle (jumbo base-ten blocks)
• Provide extra time for completion of tasks
• Use color-coding: blue for tens, red for ones
• Reduce number of problems required (focus on quality over quantity)
• Allow use of a number line or hundred chart as support
• Provide pre-drawn tens and ones that learners can color/circle
• Break instructions into smaller, sequential steps with visual cues
• For learners with visual processing difficulties, use tactile materials and verbal explanations

✅ What worked well:

[To be completed after lesson – Consider: Did learners engage with concrete materials? Were explanations clear? Did the hook capture attention? What strategies led to the most success?]

🔧 What could be improved:

[To be completed after lesson – Consider: Did timing work well? Were any learners confused? Do any concepts need reteaching? Should I adjust the pace or approach?]

📝 Notes for next lesson:

[To be completed after lesson – Consider: Which learners need additional support? Are we ready to introduce regrouping? Should we spend more time on this concept? What follow-up activities would be beneficial?]