Mathematics - Term 2 - Week 9

Number sense is the ability to understand, relate, and connect numbers. It involves recognizing the magnitude of numbers, understanding their relationships, and being able to manipulate them in various ways. For example, knowing that 50 is greater than 30 and understanding how to round numbers to the nearest ten are essential skills. This week, we will explore how to use number lines and visual models to represent numbers and their relationships.

Let's take the number 67. To round it to the nearest ten, we look at the digit in the ones place, which is 7. Since 7 is 5 or greater, we round up. Therefore, 67 rounded to the nearest ten is 70. If we had 62, we would round down to 60 because the ones digit is 2, which is less than 5.

Now, let's practice rounding some numbers together. I will give you a number, and you will tell me how to round it to the nearest ten. For example, if I say 84, what is it rounded to? (Students respond: 80). Great! Let's try a few more: round 45, 29, and 73. Discuss your answers with a partner and explain your reasoning.

For your independent practice, solve the following problems on your own. 1) Round 56 to the nearest ten. 2) What is 34 + 29? Show your working clearly. 3) If you have 120 apples and you give away 45, how many do you have left? 4) Explain how you arrived at your answers and be prepared to share your strategies with the class.

• 70
• 75
• 80
• 72

Answer: 70

Since the ones digit is 3, we round down to 70.

• 45
• 54
• 30
• 60

Answer: 60

60 is the largest number among the options.

Answer: 125

Adding the two numbers gives you 125.

• 80
• 85
• 90
• 75

Answer: 80

The ones digit is 2, so we round down to 80.

Answer: 15

150 divided by 10 equals 15.

• 43
• 44
• 45
• 42

Answer: 43

Adding 29 and 14 gives you 43.

Answer: 125

200 minus 75 equals 125.

• 60
• 70
• 65
• 68

Answer: 70

Since the ones digit is 7, we round up to 70.