Lesson Notes By Weeks and Term v5 - Grade 2
Numbers 0–99: place value and operations (Grade 2) – Week 5 focus
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Numbers 0–99: place value and operations (Grade 2) – Week 5 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: 5
Theme: General lesson support
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This week, we're diving deeper into understanding numbers from 0 to
9
9. We will be focusing on place value (tens and units) and how to use this understanding to perform basic addition and subtraction. This is extremely important because it helps us count money, share sweets with friends, measure ingredients when baking vetkoek with Gogo, and understand the numbers all around us in South Africa. Imagine trying to buy sweets at the spaza shop if you don’t understand how much things cost!
Place Value: Tens and Units Every number has a value depending on its position or "place." When we talk about numbers between 0 and 99, we have two places: the tens place and the units (or ones) place.
Units: The units place tells us how many ones we have. For example, in the number 7, we have 7 ones.
Tens: The tens place tells us how many tens we have. A ten is a group of 10 ones. For example, in the number 30, we have 3 tens. Let's look at the number
4
5. The digit 4 is in the tens place. This means we have 4 tens, which is 4 x 10 =
4
0. The digit 5 is in the units place. This means we have 5 ones, which is 5 x 1 =
5. So, 45 is made up of 4 tens and 5 units. We can write it as 40 + 5 =
4
5. Using Concrete Materials We can use blocks or counters to help us understand place value. Imagine we have base ten blocks. Long blocks represent tens, and small cubes represent units. To represent 23, we would use 2 long blocks (2 tens = 20) and 3 small cubes (3 units = 3). Addition (Without Carrying Over) Adding numbers means putting them together to find the total. When adding a single-digit number to a two-digit number (without carrying over), we only add the units. The tens digit stays the same.
Example 1: 32 + 5 We have 3 tens and 2 units. We are adding 5 units. So, we add 2 units + 5 units = 7 units. The tens digit stays the same (3 tens).
Therefore, 32 + 5 =
3
7. Example 2: Thando has 21 marbles, and Sipho gives him 6 more. How many marbles does Thando have in total?
This is an addition problem: 21 + 6 We add the units: 1 + 6 = 7 The tens digit stays the same: 2 Thando has 27 marbles. Subtraction (Without Borrowing) Subtracting numbers means taking away from the total. When subtracting a single-digit number from a two-digit number (without borrowing), we only subtract the units. The tens digit stays the same.
Example 1: 48 - 3 We have 4 tens and 8 units. We are taking away 3 units. So, we subtract 8 units - 3 units = 5 units. The tens digit stays the same (4 tens).
Therefore, 48 - 3 =
4
5. Example 2: Zanele has 35 sweets, and she eats 4 of them. How many sweets does Zanele have left?
This is a subtraction problem: 35 - 4 We subtract the units: 5 - 4 = 1 The tens digit stays the same: 3 Zanele has 31 sweets left. Word Problems Word problems are stories that use numbers. To solve a word problem, we need to understand what the problem is asking us to do. We need to decide whether to add or subtract. Look for keywords like "in total," "altogether," "more than" (usually implies addition) or "left," "less than," "take away" (usually implies subtraction). Guided Practice (With Solutions)
Question 1: What are the tens and units in the number 64?
Solution: The digit 6 is in the tens place, so there are 6 tens (60). The digit 4 is in the units place, so there are 4 units (4).
Answer: 6 tens and 4 units.
Question 2: Represent the number 37 using base ten blocks.
Solution: We need 3 tens blocks (3 x 10 = 30) and 7 unit cubes.
Answer: 3 tens blocks and 7 unit cubes.
Question 3: Calculate 53 +
6. Solution: We add the units: 3 + 6 = 9 The tens digit stays the same: 5 Answer: 53 + 6 = 59 Question 4: Calculate 79 -
5. Solution: We subtract the units: 9 - 5 = 4 The tens digit stays the same: 7 Answer: 79 - 5 = 74 Question 5: Maria has 42 beads. She gives 2 beads to her sister. How many beads does Maria have left?
Solution: This is a subtraction problem: 42 - 2 We subtract the units: 2 - 2 = 0 The tens digit stays the same: 4 Answer: Maria has 40 beads left. Independent Practice (Questions Only) What are the tens and units in the number 81? Represent the number 15 using base ten blocks. Calculate 24 +
3. Calculate 96 -
4. David has 65 stickers. He gives 4 stickers to his friend. How many stickers does David have left? Calculate 31 +
7. Calculate 58 -
2. What number is represented by 5 tens and 9 units? Sarah has 77 crayons. She breaks 6 crayons. How many crayons does Sarah have left? Jabu has 25 apples and Peter has 4 apples. How many apples do they have together?