New
New
Year 2

Use knowledge of facts and unitising to add and subtract multiples of ten

I can use knowledge of known facts and unitising to add and subtract multiples of ten.

New
New
Year 2

Use knowledge of facts and unitising to add and subtract multiples of ten

I can use knowledge of known facts and unitising to add and subtract multiples of ten.

Lesson details

Key learning points

  1. Tens numbers can be added to or subtracted from a multiple of ten.
  2. When you add a tens number to a multiple of ten the tens number increases.
  3. When you subtract a tens number from a multiple of ten the tens number decreases.
  4. If 3 + 1 is equal to 4 then 3 tens + 1 ten is equal to 4 tens which is equal to 40
  5. If 4 - 1 is equal to 3 then 4 tens subtract 1 ten is equal to 3 tens which is equal to 30

Common misconception

Children may use counting on and back strategies instead of application of known facts and therefore be inefficient when adding and subtracting multiples of 10

Use representations to make clear links when unitising e.g. adding 2 to 3 and then adding 2 groups of 10 to 3 groups of 10, to support children in making the link. Children should be increasingly fluent in addition and subtraction within 10

Keywords

  • Add - To find the total, or sum, by combining two or more parts (addends), or to increase an amount by adding another.

  • Plus - To find the total, or sum, by combining two or more parts (addends), or to increase an amount by adding another.

  • Subtract - To partition one part from another (the subtrahend from the difference), or to decrease an amount by taking an amount away.

  • Minus - To partition one part from another (the subtrahend from the difference), or to decrease an amount by taking an amount away.

Take time in this lesson to provide practical examples to support the concept of unitising, such as bundles of 10 straws, packets of 10 pens or pencils or sticks of 10 cubes.
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).

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6 Questions

Q1.
Complete the sentence. I know that 6 + 1 = 7 so .
60 - 10 = 50
Correct answer: 60 + 10 = 70
80 - 10 = 70
Q2.
Complete the sentence. I know that 8 - 1 = 7 so .
80 + 10 = 90
Correct answer: 80 - 10 = 70
60 + 10 = 70
Q3.
Ten more than 30 is
50
Correct answer: 40
30
Q4.
Ten less than 60 is
Correct Answer: 50, fifty
Q5.
Match the equation to the correct multiple of 10
Correct Answer:40 + 10 =,50

50

Correct Answer:10 + 50 =,60

60

Correct Answer:50 - 10 = ,40

40

Correct Answer:40 - 10 =,30

30

Q6.
Jun thinks he has represented 40 + 10 = 50 but he is incorrect. What equation does this represent?
An image in a quiz
40 + 10 = 50
30 - 10 = 20
Correct answer: 30 + 10 = 40

6 Questions

Q1.
Which representation matches 4 tens + 1 ten = 5 tens?
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Q2.
Which equation is being represented?
An image in a quiz
6 tens subtract 4 tens =
6 tens add 2 tens =
Correct answer: 6 tens subtract 2 tens =
Q3.
Match the statements.
Correct Answer:I know that 4 plus 2 is equal to 6,so 4 tens plus 2 tens is equal to 6 tens.

so 4 tens plus 2 tens is equal to 6 tens.

Correct Answer:I know that 5 plus 3 is equal to 8,so 5 tens plus 3 tens is equal to 8 tens.

so 5 tens plus 3 tens is equal to 8 tens.

Correct Answer:I know that 2 plus 5 is equal to 7,so 2 tens plus 5 tens is equal to 7 tens.

so 2 tens plus 5 tens is equal to 7 tens.

Q4.
Complete the equation 6 tens = 3 tens + tens
2
Correct answer: 3
5
Q5.
Which representation could show 6 tens subtract 4 tens is equal to 2 tens?
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Q6.
Alex says, “I know that 7 minus 4 is equal to 3”. Which of the following equations would Alex’s statement help to solve?
7 tens add 3 tens =
Correct answer: 7 tens subtract 4 tens =
4 tens subtract 3 tens =