Mathematics - Term 4 - Week 5

Number sense is the ability to understand, relate, and connect numbers. It involves recognizing numbers in different forms, such as whole numbers, fractions, and decimals. This week, we will focus on how to count in various ways, including skip counting and counting backwards. We will also discuss the importance of estimating and rounding numbers to make calculations easier.

Let's look at skip counting by 5s. Starting from 0, we can count: 0, 5, 10, 15, 20, and so on. Each number is 5 more than the previous one. To visualize this, we can use a number line. If we mark these points on the line, we can see the pattern clearly. This method helps us quickly find larger numbers without having to count each one individually.

Now, let's practice counting backwards from 50. I will write the numbers on the board as we go. Start with 50, then go to 49, 48, 47, and so on. As we count, think about how each number is one less than the previous number. After we finish, we will discuss how counting backwards can help us in subtraction problems.

For your independent practice, solve the following problems on your own. 1) Count by 10s starting from 30 up to 100. 2) Write down the numbers you get when counting backwards from 25 to 1. 3) Create a visual model (like a number line or a chart) showing your skip counting by 2s from 0 to 40. Make sure to show your work clearly and be prepared to share your strategies with the class.

• 20
• 25
• 30
• 15

Answer: 20

The sequence is increasing by 5 each time, so the next number is 15 + 5 = 20.

• 1, 2, 3, 4
• 10, 9, 8, 7
• 5, 10, 15
• 0, 1, 2

Answer: 10, 9, 8, 7

Counting backwards means decreasing the numbers, as seen in the sequence 10, 9, 8, 7.

Answer: 0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30

Skip counting by 3s means adding 3 each time, resulting in the sequence listed.

• 1
• 15
• 8
• 10

Answer: 15

When counting backwards, you start from the highest number, which is 15.

Answer: Estimating helps to quickly gauge the size of a number or the result of a calculation without needing exact figures.

Estimation allows for quicker decision-making and can simplify complex calculations.

• 40
• 50
• 45
• 30

Answer: 50

When rounding 47 to the nearest ten, we look at the digit in the ones place, which is 7, and round up to 50.

Answer: 0, 4, 8, 12, 16

Counting by 4s means adding 4 each time, resulting in the sequence listed.

• Number line