Mathematics - Term 3 - Week 7

Number sense refers to a person's ability to understand, interpret, and work with numbers. It includes recognizing numbers, understanding their relationships, and being able to manipulate them in various ways. In this lesson, we will explore how to count in different ways, such as counting by 2s, 5s, and 10s, and how to use these skills in real-life situations. We will also discuss the importance of estimating and making reasonable guesses when working with numbers.

Let's practice counting by 5s. Start from 0 and list the first ten numbers you get: 0, 5, 10, 15, 20, 25, 30, 35, 40, 45. Notice how each number increases by 5. This method helps us quickly calculate larger numbers, such as how many 5s are in 100. To find this, we can divide 100 by 5, which equals 20. Therefore, there are 20 groups of 5 in 100.

Now, let's use a number line to visualize counting by 10s. Draw a number line on the board and mark the numbers 0 to 100. As we count by 10s, we will place a dot at each multiple of 10: 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100. This visual representation helps us see the gaps between the numbers and understand the concept of intervals. After this, I will ask you to count by 10s from 50 to 100 and mark the points on your own number line.

Now it's your turn to solve some problems using your number sense skills. Here are a few questions: 1) If you have 3 bags with 8 apples each, how many apples do you have in total? 2) Estimate how many minutes are in 3 hours. 3) If you count by 2s starting from 0, what is the 15th number you will say? Write down your answers and show your working clearly. Remember to check your calculations and correct any mistakes.

• 20
• 25
• 30
• 15

Answer: 20

The sequence increases by 5 each time, so the next number after 15 is 20.

• 10
• 20
• 30
• 40

Answer: 20

200 divided by 10 equals 20, meaning there are 20 groups of 10 in 200.

Answer: 18

The sequence is 0, 3, 6, 9, 12, 15, 18. The 7th number is 18.

• Calculating 47 + 36 exactly
• Rounding 47 to 50 and 36 to 40
• Counting every item one by one
• Using a calculator

Answer: Rounding 47 to 50 and 36 to 40

Estimating involves rounding numbers to make calculations easier.

Answer: 62

Adding 25 and 37 gives you 62.

• 10
• 24
• 18
• 12

Answer: 24

4 groups of 6 means 4 multiplied by 6, which equals 24.

Answer: 20

100 divided by 5 equals 20.

• 20
• 18
• 22
• 15

Answer: 20

Counting by 2s gives you 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20. The 10th number is 20.