Count groups of 10 in decade numbers | Maths | Quizalize & Oak National Academy

Starter quiz

This is not 1 group of 10 because __________

it has 10 objects.

it does not have 10 objects. ✓
Which picture is representing 1 ten?

Focusing on the 9 fingers pointing up.
How many tens can you see?

10

1 ✓

0
Match the groups of 10s to the number of tens they represent.

4 tens

⇔

4 groups of 10 ✓

3 tens

⇔

3 groups of 10 ✓

10 tens

⇔

10 groups of 10 ✓

7 tens

⇔

7 groups of 10 ✓
Which image shows 4 tens?
How many tens can you see?

3

2

1 ✓

This number ends in 0. This tells me that it is a ______ number.

'decade' ✓
How many tens are in this picture?

8 ✓

80
How many pizza slices are there altogether?

8

70 ✓

80
Which picture shows 40?
Look at the number 90. What does the 9 represent?

9

9 tens. ✓

It is a decade number.
Match the numbers that represent the same amount.

70

⇔

7 tens ✓

50

⇔

5 tens ✓

30

⇔

3 tens ✓

10

⇔

1 ten ✓

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You can count groups of 10 in two ways.
You can count groups of 10 using decade numbers.
You can look at the digit before zero to find out how many tens are in a decade number.

When objects are in 10s, children may count the number of tens rather than the amount altogether.

Introduce errors involving confusion between the number of tens and the amount altogether for children to reason about.

Group - Objects that are gathered together in a set can be said to be in a group.
Decade numbers - These are the multiples of ten which mark the tens boundary where the pattern of counting changes.
Represent - The word represent tells you what something is worth or what it means or tells you.