New
New
Year 2

Add and subtract one to or from a two-digit number within a decade

I can add and subtract 1 to and from a 2-digit number within a decade.

New
New
Year 2

Add and subtract one to or from a two-digit number within a decade

I can add and subtract 1 to and from a 2-digit number within a decade.

Lesson details

Key learning points

  1. Finding one more is the same as adding 1. Finding one less is the same as subtracting 1
  2. Numbers that are one more or one less than each other have a difference of one.

Common misconception

The language of one more or one less than can confuse children, so 55 is one more than ? may be interpreted as 55 plus 1

Encourage children to articulate and explain in full sentences alongside number lines to support the understanding of the different ways to articulate the concept. Use stem sentences to support with this and display them around the classroom.

Keywords

  • One more - The number that is one more than another is the result of adding 1 to that number

  • One less - The number that is one less than another is the result of subtracting 1 from that number

  • Difference - The result of subtracting one number from another. How much one number differs from another.

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).

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6 Questions

Q1.
Which picture shows one less than 12?
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
Q2.
Which number would complete the part-part-whole model correctly?
An image in a quiz
1
Correct answer: 17
18
19
Q3.
Fill in the missing number. ___ is one more than 8
Correct Answer: 9, nine
Q4.
Find the missing number.
An image in a quiz
Correct Answer: 3, three
Q5.
Alex is thinking of two numbers which have a difference of 1 One of the numbers is 15 What could the other number be?
Correct answer: 14
15
Correct answer: 16
17
Q6.
Find the missing number.
An image in a quiz
Correct Answer: 18, eighteen

6 Questions

Q1.
Use a number line or one hundred square to help you find the missing number.
An image in a quiz
Correct Answer: 64, sixty-four, sixty four
Q2.
Which picture shows one less than 37?
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
Q3.
Which number would complete the part-part-whole model correctly?
An image in a quiz
Correct Answer: 61, sixty-one, sixty one
Q4.
Use the part-part-whole model to help you complete the equation. 43 - = 42
An image in a quiz
Correct Answer: 1, one
Q5.
Complete the stem sentence. is one more than 76
Correct Answer: 77, seventy-seven, seventy seven
Q6.
Tick the equations that would represent, '25 is one less than 26'
Correct answer: 26 - 1 = 25
25 - 1 = 24
Correct answer: 25 = 26 - 1
Correct answer: 25 + 1 = 26