Number, Fractions and Money

Objectives

To count in 3s, making links to multiplication.

To identify multiples of 3.

Resources

100 bead string | 📄 0–30 beaded line | Interactive Number Grid (Mathsframe) | 📄 Counting in 3s

Vocabulary

pattern | times tables

Today's Lesson

Introduction

ACCESS - Interactive Number Grid (Mathsframe)

Whisper as you point to each number, but shout and highlight the multiples of 3: 1, 2, 3, 4, 5, 6 … 30.

Now just count the highlighted numbers.

Say:

We are counting on in 3s, adding 3 each time, so 3 + 3 is 6, 6 + 3 is 9, 9 + 3 is 12, and so on. These are multiples of 3.

Mirror this counting using a 100 bead string, pushing all the beads to the right then moving a group of 3 to the left each time you ‘shout’ a multiple of 3 from the Interactive Number Grid.

Now highlight all multiples of 3.

Ask:

Can you describe the pattern of these multiples?

Discuss the diagonal pattern.

Say:

I wonder whether there is a mathematical rule to help us spot if a number is a multiple of 3?

Give your student a moment to think about this, then ask:

Add the digits together in each number. What do you notice? (They add to 3, 6 or 9: the ‘digit sum’ is 3, 6 or 9).

This video introduces multiples of 3 using the activities above.

Try bigger multiples of 3, for example, 60 and 63. How about 66? We get 12, but what if you add 1 and 2? Sometimes you have to add the digits twice.

Say:

It would take a very long time to count on in 3s to 204, but this always happens, so we can always check if numbers are multiples of 3! (2 + 0 + 4 = 6, so 204 is a multiple of 3: 68 lots of 3!)

Say:

Let’s try this for some other big numbers.

Write 123, 412, 339 and 450 on the board. Find the digit sum each number to see if it is a multiple of 3.

Show your student the 📄 0–30 beaded line. Count in 3s along it, marking multiples of 3. What are four 3s? Nine 3s? How did you work it out? Draw 4 hops of 3 to confirm.

Explain:

We can write 3 + 3 + 3 + 3 = 12 but it’s quicker to write 4 × 3 = 12.

Remind your student that the symbol ‘×’ is ‘lots of’. 4 × 3 is 4 lots of 3.

Main Activity

Ask your student to complete the 📄 Counting in 3s sheet, with support as necessary, gradually increasing their independence as they progress.

Citations

[1] mathsframe.co.uk