Addition of 2 Digit Numbers

Week 2

Learning Outcome

Uses real-world situations and concrete objects to model and solve addition problems using abacus and place value models.

Objective

Children will be able to use an abacus and draw place value models to show and solve addition problems involving two-digit numbers, with and without regrouping.

Prerequisites

Children can perform single-digit addition.

Pre-teach Vocabulary

Children should be familiar with the terms such as, place value, add, plus and equal to.

Introduction: Addition on Abacus

  • The teacher could begin by reviewing 2-digit addition using flashcards of addition.
  • For example, the teacher will ask the children to show the addition for the problem 23+14 =? using blocks on an A4 sheet and to show the answer. 

The teacher will encourage the children to respond with more examples.

Materials required:

  • Abacus
  • Whiteboard and markers
  • Chart of place value (Tens and Ones)
  • Worksheets for practice
  • Coloured pencils
  • Math notebooks

Teaching Method: I Do – We Do – You Do

I DO (Teacher Modeling):

Example Problem: 54 + 23 = ?

  1. Display the problem on the board.
  2. Using the abacus:
    • Place 5 beads in the tens column and 4 beads in the ones.
    • We are adding 23 with 54. That is 2 tens and 3 ones.
    • So I will add 3 ones beads to 4 ones beads and count. It is 7. 
    • Add 2 tens beads to 5 tens beads and count. It is 7.
    • So, the answer is 77.
  3. Drawing:
    • Provide children with a picture of a place value abacus (Tens and Ones).
    • Say: Let’s show 54 on the abacus by drawing beads.
      1. In the Tens column, draw 5 beads.
      2. In the Ones column, draw 4 beads.
    • Say, now we need to add 23 with 54. That is 2 tens and 3 ones.
      1. Add ones. It is 7. Add tens. It is 7.
      2. So, the answer is 77.

Drawing Beads on Abacus:

 Example Problem: 56 + 38 =?

  1. Draw 5 beads in the Tens column and 6 beads in the Ones column on a place value abacus template to build the number 56.
  2. Draw 3 beads in the Tens column and 8 beads in the Ones column on a place value abacus template to build the number 38.
  3. We have to add 38 with 56. Add Ones column. It is 14.
  4. 14 is greater than 10. So, we need to regroup.
  5. Regrouping:
    • Trade 1 Ten bead for 10 Ones beads.
    • Add 1 Tens bead to 5 Tens beads. This is trading.
    • Now, there are 6 beads in the Tens column and 4 ones in the Ones column.
  6. Add:
    • Ones column shows 4 Ones
    • Tens column total is 6 + 3 = 9 
  7. So, the final answer is 94.
  8. Talk through each step slowly. First we add the ones. If the total is more than 10, then trade 10 Ones for one Ten. Then add the Tens column.

WE DO (Guided Practice):

Example Problem: 36 + 29 =?

  1. Ask the children to help you build the number 36 on the abacus: 3 tens and 6 ones.
  2. Then build number 29.It is 2 Tens and 9 Ones.
  3. How many Ones are there in total?
    • Children respond: 15
  4. 15 is greater than 10. 
  5. Guide them to regroup:
    • Trade 1 ten (10 beads) for 10 ones. Now we have 4 tens and 5 ones.
    • Add 2 tens to 4 tens. We get 6 tens.
    • So, the final answer is 65.
  6. Do the same problem using drawing.

Drawing Beads on Abacus:

Example Problem: 36 + 29

  1. Draw 3 beads in the Tens column and 6 beads in the Ones column on a place value abacus template.
  2. Then draw number 29. It is 2 Tens and 9 Ones.
  3. Add ones. It is 15
  4. Regrouping Step:
    • Trade 1 ten bead for 10 Ones beads.
    • Add1 bead to the Tens column and cross out 10 beads in the Ones column. This is trading.
    • Now, we have 4 beads in the Tens column and 5 beads in the Ones column.
    • Add Tens column. We get 4+2 = 6 in Tens column.
    • So, the final answer is 65.
  5. Talk through each step slowly. First we check the ones column. First we add the ones. If the total is more than 10, then trade 10 Ones for one Ten. Then add the Tens column.
  6. Ask children guiding questions such as, why did we regroup? What helped us find the answer?

YOU DO (Independent Practice):

  • Children are given addition problems like     
    1. 47 + 25 = ?
    2. 61 + 34 = ?
    3. 55 + 27 = ?
  • Children will:
    1. Use their abacus to model and solve.
    2. Draw the problem using place value visuals in their notebooks.
    3. Write the final answer.

Video: Addition on Abacus – Coming soon

ISL Video: Addition on Abacus – Coming soon

LTM: DIY Flashcards – Coming soon

LTM: Printable Flashcards – Coming soon

Activity 1: Shopping with Addition

Objective: To apply addition of two-digit numbers in real-life situations by using play money to simulate shopping.

Importance of the activity for children:

Helps in developing:

  1. Gross motor skills (Walking) 
  2. Fine motor skills (hand-eye coordination, writing)
  3. Cognitive skills (Counting, critical thinking, decision-making)
  4. Social skills (Cooperation, playing together, discussing)
  5. Language skills (Articulating)
  6. Emotional skills (Builds confidence in numeracy, promotes a sense of achievement that boosts self-esteem, and encourages pride in learning new skills) 

Resources required:

  • Play money (bills and coins or printable sets)
  • Price tags or picture cards of classroom items (₹10 to 99 in value)
  • Shopping worksheets or recording sheets (With Abacus)
  • Pencil and eraser
  • (Optional) Cash register toy or pretend wallet

Setting for the activity:
The activity can be done indoors with a store area or shopping table set up.

Type of activity: Individual Activity (can also be done in pairs)

Preparation of activity:

  • Label classroom items or printed images with prices between ₹10 and ₹99
  • Prepare a set amount of play money for each Child (e.g., ₹100)
  • Create simple recording sheets with columns: Item | Price | Paid | Change
  • Role badges for “shopkeeper” and “customer” are optional.     

Role of the teacher: Demonstrator, observer, and facilitator.

Procedure:

  1. Introduction:
    • The teacher says, “Today you are going shopping! You’ll choose items and figure out how much money you had spent in shopping using addition.”
  2. Activity Steps:
    • Each Child receives a set amount of play money (e.g., ₹100).
    • Each child is instructed to buy two items only.
    • They select an item (e.g., a toy with a ₹28 price tag) and a chocolate bar for ₹ 35.
    • They add to find out how much they had spent on both items. (₹28+₹35=₹63).
    • They can use an abacus, base ten blocks, or drawings to help with addition.
    • They write the addition sentence and write the answer on their sheet.
    • Repeat for 2 or 3 items for each child.

Suggested Variations:

  • Give children a scenario. You bought a pencil for ₹15 and a note book for ₹20 and got back ₹ 5 as balance from the shopkeeper. How much did you give the shopkeeper? Children use addition and subtraction to solve the mystery (₹15 + ₹20 = ₹35; 35+5 =40). If the question is how much balance you should get? Solution is ₹40 – ₹35= ₹5. Children can explain their thinking either verbally or in writing.

Observations:

The teacher observes the children engaged in the activity to find:

  1. Can the children set up and solve a two-digit addition problem accurately?
  2. Do the children recognise when regrouping is needed?
  3. Can the children use an efficient strategy like mental math, drawing, and manipulatives?

Conclusion:
The children will be able to solve 2- digit addition problems using manipulatives.

Video: Shopping with addition – Coming soon

ISL Video: Shopping with addition – Coming soon

Activity 2: Roll and Add

Objective: 
To solve addition problems by modelling numbers on the abacus using dice rolls and adding beads to find the answer.

Importance of the activity for children:

Helps in developing:

  1. Fine motor skills (Moving abacus beads)
  2. Cognitive skills (Understanding place value, visualising addition)
  3. Social skills (Cooperation, taking turns with dice)
  4. Language skills (Articulating)
  5. Emotional skills (Builds confidence in numeracy, promotes a sense of achievement that boosts self-esteem, and encourages pride in learning new skills) 

Resources required:

  • Two six-sided dice
  • A4 sheet for recording answers
  • Pencil and eraser
  • Crayons (optional for colour coding tens and ones beads)
  • Flashcards (with pre-written subtraction sentences, optional)
  • Abacus (physical or printed template)

Setting for the activity: 
The activity can be done indoors or outdoors, depending on the space availability.

Type of activity:
Individual activity (can be adapted for pairs or small groups)

Preparation of activity:
The teacher will ensure the availability of resources like dice, abacus (or templates), and worksheets. Flashcards with addition problems may be prepared in advance.

Role of the teacher: Demonstrator, observer, and facilitator.

Procedure:

  1. Each child gets:
    • Two dice to form an addition problem
    • An A4 sheet to record answers
    • An abacus or template for visualizing numbers
  2. The teacher gives instructions:
    • The first number is modelled on the abacus using correct beads (tens and ones).
    • The second number tells how many beads to add to the abacus.
    • Example: In 34 +21=?
      1. Represent 34 on the abacus: 3 beads in the tens place, 4 in the ones place.
      2. Add 2 tens bead and 1 one bead (for 21).
      3. Count the beads: 5 tens and 5 ones. The answer is 55.
  3. Children repeat the activity with new addition problems using dice.

Observation:
The teacher observes the children engaged in the activity to find:

  • Are the children able to model 2-digit numbers accurately using abacus beads?
  • If they are able to add the correct number of beads to solve the problem?

Conclusion:
The children are able to add 2- digit numbers with and without regrouping. 

Video: Roll and add- Coming soon

ISL Video: Roll and add – Coming soon

Assessment

The teacher can give the practice worksheet to children, which can be followed by an assessment worksheet.

Practice Worksheet – Coming soon

Practice Worksheet (Enlarged) – Coming soon

Assessment Worksheet – Coming soon

Assessment Worksheet (Enlarged) – Coming soon

Cross-Curricular Connection:

  • Language Class:
    Children can be instructed to create and solve small word problems involving addition and share them with others.
  • Art Class:
    Children can draw the answer to the math problem given. For example, the problem can be 20 flowers + 18 flowers =? Children can find the answer using manipulatives and draw the answer, 38 flowers.
  • Physical Education Class: “Scoring and Adding” (Mini Sports)
    Example: Basketball
    • Two children can be given 20 chances each to throw the ball in the basket.
    • Count the successful throw for each child.
    • Add the total successful hits.
    • The pair with the highest total is declared the winner.

Check list for teacher:

ActivityYesNoSometimes
Children can:
Use abacus or draw abacus to do 2- digit addition without regrouping
Use abacus or draw abacus to 2 – digit addition with regrouping
Apply addition of two-digit numbers in real-life situations
Understand the word problems in addition and solve them
Complete the activities in the given time
Do the activities independently
Express verbally and through actions, expressions or gestures
Enjoy teamwork, appreciate others, and are willing to learn from others

Home Activity

Assessment Worksheet – Coming soon

Assessment Worksheet (Enlarged) – Coming soon

Teacher Resource Document – Coming soon

Source and Attribution of images:
All images used in the above Assets and Aids are originally created.
This digital material has been developed by the Sri Sathya Sai Vidya Vahini Inclusive Education Project, a unit of Sri Sathya Sai Central Trust, Prasanthi Nilayam, as a collaborative offering in the service of our nation.