Lesson Notes By Weeks and Term v5 - Grade 2
Numbers 0–99: place value and operations (Grade 2) – Week 4 focus
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Numbers 0–99: place value and operations (Grade 2) – Week 4 focus
Download the Lessonotes Mobile South Africa app for faster lesson access on Android and iPhone.
Subject: Mathematics
Class: Grade 2
Term: 1st Term
Week: 4
Theme: General lesson support
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This week, we’re diving deeper into numbers between 0 and 99! Understanding these numbers is super important because we use them every single day in South Africa. Think about buying sweets at the spaza shop, counting the oranges in a bag from the market, or even checking the bus number to get home. Learning about place value helps us understand what each digit in a number means, and that makes adding, subtracting, and problem-solving much easier. Imagine trying to share 56 sweets fairly between 2 friends if you didn't know that 56 is made up of 5 tens and 6 ones! This week, we’ll be focusing on breaking down numbers, building them back up, and using that knowledge to solve simple problems.
Place Value: Tens and Ones Every number is made up of digits, and the place of each digit tells us its value. For numbers between 0 and 99, we have two places: Tens Place: The digit in this place tells us how many groups of ten we have.
Ones Place: The digit in this place tells us how many single units (ones) we have.
Let's look at the number 37: The digit 3 is in the tens place. This means we have 3 groups of ten, or
3
0. The digit 7 is in the ones place. This means we have 7 single units, or
7. So, 37 = 30 +
7. We can represent this using counters: 3 rows of 10 counters and 7 single counters.
Example 1: Understanding Place Value What does the number 62 represent? The 6 is in the tens place, so it represents 6 tens, or
6
0. The 2 is in the ones place, so it represents 2 ones, or
2. Therefore, 62 = 60 +
2. Example 2: Representing Numbers How can we represent the number 85 using place value? We have 8 tens, which is
8
0. We have 5 ones, which is
5. So, 85 = 80 +
5. We can draw this as 8 rows of 10 blocks and 5 single blocks. Addition without Regrouping When adding two numbers, we add the ones together and the tens together separately, as long as the sum of the ones is less than
1
0. This is called addition without regrouping.
Example 3: Adding without Regrouping Let’s add 23 +
3
4. Break down the numbers: 23 = 20 + 3 34 = 30 + 4 Add the tens together: 20 + 30 = 50 Add the ones together: 3 + 4 = 7 Combine the tens and ones: 50 + 7 = 57 Therefore, 23 + 34 =
5
7. We can also visualize this. Imagine 2 stacks of 10 sweets (representing 20) and 3 individual sweets (representing 3) being combined with 3 stacks of 10 sweets (representing 30) and 4 individual sweets (representing 4). In total, you’d have 5 stacks of 10 (50) and 7 individual sweets (7).
Example 4: Another Addition Example Calculate 41 +
1
5. Break down the numbers: 41 = 40 + 1 15 = 10 + 5 Add the tens together: 40 + 10 = 50 Add the ones together: 1 + 5 = 6 Combine the tens and ones: 50 + 6 = 56 Therefore, 41 + 15 =
5
6. Subtraction of a 1-digit number without Regrouping When subtracting a 1-digit number from a 2-digit number, we only need to subtract from the ones place if we are not regrouping (borrowing).
Example 5: Subtracting without Regrouping Let’s subtract 5 from
3
8. Break down the number: 38 = 30 + 8 Subtract from the ones: 8 - 5 = 3 Combine tens and ones: 30 + 3 = 33 Therefore, 38 - 5 =
3
3. Imagine you have 38 marbles. You give 5 marbles away. You are left with 33 marbles.
Example 6: Another Subtraction Example Calculate 79 -
4. Break down the number: 79 = 70 + 9 Subtract from the ones: 9 - 4 = 5 Combine tens and ones: 70 + 5 = 75 Therefore, 79 - 4 =
7
5. Guided Practice (With Solutions)
Question 1: Represent the number 54 using tens and ones.
Solution: 54 has 5 in the tens place, meaning 5 tens or 50. 54 has 4 in the ones place, meaning 4 ones or
4. Therefore, 54 = 50 +
4. We can represent this with 5 rows of 10 blocks and 4 individual blocks.
Question 2: Calculate 16 +
4
2. Solution: Break down the numbers: 16 = 10 + 6 42 = 40 + 2 Add the tens together: 10 + 40 = 50 Add the ones together: 6 + 2 = 8 Combine the tens and ones: 50 + 8 = 58 Therefore, 16 + 42 =
5
8. This involves breaking down the numbers into their place values and adding each place value separately before combining the totals.
Question 3: Calculate 67 -
2. Solution: Break down the number: 67 = 60 + 7 Subtract from the ones: 7 - 2 = 5 Combine tens and ones: 60 + 5 = 65 Therefore, 67 - 2 =
6
5. This method isolates the operation to the ones place, making it easier.
Question 4: Sipho has 21 marbles and Thando has 35 marbles. How many marbles do they have together?
Solution: Identify the operation: The problem asks for how many marbles they have "together", so we need to add.
Set up the problem: 21 + 35 Break down the numbers: 21 = 20 + 1 35 = 30 + 5 Add the tens together: 20 + 30 = 50 Add the ones together: 1 + 5 = 6 Combine the tens and ones: 50 + 6 = 56 Therefore, Sipho and Thando have 56 marbles together. Independent Practice (Questions Only) What does the digit 7 represent in the number 73? What does the digit 2 represent in the number 29? Write the number 91 in terms of tens and ones. Calculate 32 +
1
7. Calculate 54 +
2
5. Calculate 88 -
6. Calculate 46 -
3. Nomusa has 43 apples. She gives 2 apples to her friend. How many apples does Nomusa have left? David has 14 rand and his sister has 23 rand. How much money do they have in total? Write a number that has 6 tens and 8 ones.