New
New
Year 1

Crossing the tens boundary counting forwards

I can count forwards from 1-100, crossing the tens boundary

New
New
Year 1

Crossing the tens boundary counting forwards

I can count forwards from 1-100, crossing the tens boundary

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Lesson details

Key learning points

  1. The numbers from 0 to 100 have patterns that can help us to count across the tens boundary.
  2. They are arranged differently on a number track and on a one hundred square.
  3. We can count the numbers in two ways.
  4. When a whole number ends in a 9, it is always followed by a decade number.

Common misconception

Confusion between the number after 29, 39 etc. so saying 29,20 or twenty-none, twenty -ten.

Explicitly look at the numbers that follow a number ending in 9 using stem sentence to support.

Keywords

  • Tens boundary - This is where the pattern of counting changes at the start of the number to show a new decade has started.

  • Decade number - This is a multiples of ten which marks the tens boundary where the pattern of counting changes.

Provide regular, varied counting opportunities, e.g. rote count, count along number track and 100 squares and count familiar objects that have been grouped in tens and ones.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Video

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6 Questions

Q1.
Which of these rows from the one hundred square should come last when counting forwards?
An image in a quiz
Correct answer: the seventies
the sixties
the fifties
Q2.
Sam is counting the rows on the one hundred square backwards. They count the forties, the thirties. Which row will they say next?
An image in a quiz
Correct answer: the twenties
the fifties
Q3.
Sort these numbers in the order you would say them when counting forwards along the row of the one hundred square.
1 - 71
2 - 72
3 - 73
Q4.
Sort these numbers in the order you would say when counting backwards along the row of the one hundred square.
1 - 87
2 - 86
3 - 85
Q5.
Sam is counting along the sixties row. Which number will they say next?
An image in a quiz
4 tens 6
1 ten 6
Correct answer: 6 tens 4
Q6.
Numbers can be said in different ways. Match the numbers to the correct way to say it.
Correct Answer:35,3 tens 5

3 tens 5

Correct Answer:53,5 tens 3

5 tens 3

Correct Answer:28,2 tens 8

2 tens 8

Correct Answer:82,8 tens 2

8 tens 2

6 Questions

Q1.
On the one hundred square, a number ending in a 9 is always followed by a __________.
one
one hundred
Correct answer: decade number
Q2.
Match the rows on the one hundred square to the correct decade numbers on that row.
Correct Answer:the thirties,40

40

Correct Answer:the forties,50

50

Correct Answer:the fifties,60

60

Q3.
Lucas is counting forwards and taps this number on his Gattegno chart. What number will he tap next?
An image in a quiz
48
40
Correct answer: 50
Q4.
Andeep is counting. What number will he say next?
An image in a quiz
8 tens
Correct answer: 9 tens
8 tens 10
Q5.
When counting forwards, which counting sequence is correct?
28, 29, 20, 21
28, 29, 40, 41
Correct answer: 28, 29, 30, 31
Q6.
Look at the picture. I’m thinking of a number that ends in 4. When I count forwards, I say it after 40. What is my number?
An image in a quiz
34
Correct answer: 44
43

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