Lesson Notes By Weeks and Term v5 - Grade 2

Lesson Video

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Performance objectives

• Find the place value of tens and ones.
• Break down numbers into tens and ones.
• Add two-digit numbers.
• Subtract two-digit numbers.
• Solve simple word problems.

Lesson summary

This week, we're diving deeper into numbers from 0 to

9

9. Understanding how numbers are made up of tens and ones (place value) is like having a secret code to unlock bigger and more complex maths problems. It also helps us understand how money works in South Africa – knowing the difference between a R10 note and a R1 coin is all about place value! We'll also be adding and subtracting these numbers, which is something we do every day, like when sharing sweets with friends or figuring out how much money we need to buy a packet of chips. Mastering these skills will set you up for success in future maths topics and in your everyday lives.

Lesson notes

Place Value: Tens and Ones Every number has a value, and the place where a digit sits in a number tells us its value. In a two-digit number, the digit on the right is in the ones place, and the digit on the left is in the tens place.

Ones: The ones place tells us how many individual units we have. For example, in the number 7, we have 7 ones.

Tens: The tens place tells us how many groups of ten we have. For example, in the number 30, we have 3 tens. 3 tens are equal to 30 ones. Let's look at the number

4

2. The digit 2 is in the ones place, so we have 2 ones. The digit 4 is in the tens place, so we have 4 tens. That means 42 is made up of 4 tens (40) and 2 ones.

Example 1: The number 68. 6 is in the tens place. It represents 6 tens, which is 60. 8 is in the ones place. It represents 8 ones, which is

8. So, 68 = 60 + 8 Example 2: The number 91. 9 is in the tens place. It represents 9 tens, which is 90. 1 is in the ones place. It represents 1 one, which is

1. So, 91 = 90 + 1 Decomposing Numbers Decomposing a number means breaking it down into its tens and ones. This helps us understand the value of each digit and makes adding and subtracting easier.

Example 1: Decompose the number 57. 57 = 50 + 7 (5 tens and 7 ones)

Example 2: Decompose the number 23. 23 = 20 + 3 (2 tens and 3 ones) Adding Two-Digit Numbers (Without Regrouping) When adding two-digit numbers, we add the ones first and then the tens. It's important to keep the ones and tens separate!

Example 1: 24 + 32 = ?

Step 1: Add the ones: 4 + 2 = 6 Step 2: Add the tens: 20 + 30 = 50 Step 3: Combine the results: 50 + 6 = 56 Therefore, 24 + 32 = 56 Example 2: 45 + 13 = ?

Step 1: Add the ones: 5 + 3 = 8 Step 2: Add the tens: 40 + 10 = 50 Step 3: Combine the results: 50 + 8 = 58 Therefore, 45 + 13 = 58 We can also use a number line to help us add. Start at the first number and then jump forward the number of tens and ones in the second number. Subtracting Two-Digit Numbers (Without Regrouping) Subtracting two-digit numbers is similar to adding, but instead of adding, we take away. We subtract the ones first, then the tens.

Example 1: 58 - 23 = ?

Step 1: Subtract the ones: 8 - 3 = 5 Step 2: Subtract the tens: 50 - 20 = 30 Step 3: Combine the results: 30 + 5 = 35 Therefore, 58 - 23 = 35 Example 2: 86 - 41 = ?

Step 1: Subtract the ones: 6 - 1 = 5 Step 2: Subtract the tens: 80 - 40 = 40 Step 3: Combine the results: 40 + 5 = 45 Therefore, 86 - 41 = 45 Again, we can use a number line. Start at the first number and jump backward the number of tens and ones in the second number. Guided Practice (With Solutions)

Question 1: What is the value of the digit 3 in the number 37?

Solution: The digit 3 is in the tens place. So, it represents 3 tens, which is

3

0. Commentary: This question checks the understanding of place value. It emphasizes the difference between the digit itself and its value based on its position.

Question 2: Decompose the number 64 into tens and ones.

Solution: 64 = 60 + 4

Commentary: This reinforces the idea of breaking down a number into its constituent tens and ones.

Question 3: Calculate 25 + 14 using the place value method.

Solution: Step 1: Add the ones: 5 + 4 = 9 Step 2: Add the tens: 20 + 10 = 30 Step 3: Combine the results: 30 + 9 = 39 Therefore, 25 + 14 = 39

Commentary: This shows the step-by-step process of addition, focusing on adding the ones and tens separately.

Question 4: Calculate 49 - 26 using the place value method.

Solution: Step 1: Subtract the ones: 9 - 6 = 3 Step 2: Subtract the tens: 40 - 20 = 20 Step 3: Combine the results: 20 + 3 = 23 Therefore, 49 - 26 = 23

Commentary: This demonstrates subtraction using the same place value method as addition. Independent Practice (Questions Only) What is the value of the digit 7 in the number 72? Decompose the number 81 into tens and ones. Calculate 33 +

2

5. Calculate 67 -

3

4. Sarah has 42 marbles, and John has 27 marbles. How many marbles do they have altogether? A baker baked 55 cookies and sold

3

2. How many cookies are left? Write the number that has 6 tens and 5 ones. Write the number that has 9 tens and 0 ones. The shop owner has 88 apples, and he sells 45 apples. How many apples does he have left? Thando has 21 toy cars, and Sipho gives him 15 more. How many toy cars does Thando have now?