New
New
Year 2

Solve problems by adding and subtracting tens and ones

I can solve problems that require the addition and subtraction of tens and ones.

New
New
Year 2

Solve problems by adding and subtracting tens and ones

I can solve problems that require the addition and subtraction of tens and ones.

Lesson details

Key learning points

  1. When tens and ones are combined to make a two-digit number, it can be represented as an addition equation.
  2. When a two-digit number is partitioned into tens and ones, it can be represented as a subtraction equation.
  3. We can use bar models to help us understand and represent a problem.

Common misconception

Children may confuse addition and subtraction on bar models and in problems, so may add instead of subtracting or subtract instead of adding.

Cuisenaire rods or strips of paper with numbers written upon them can be manipulated as bar models that represent a problem or equation. This way, the structure of the mathematics can be discussed.

Keywords

  • Addition - Finding the total, or sum, by combining two or more numbers.

  • Subtraction - Taking one number away from another.

  • Part - A piece or section of a whole

  • Whole - All of something; complete.

As the focus of this lesson is on the structure of the mathematics within problems and how this is represented as a bar model, children should be confident with the addition and subtraction of tens and ones before attempting to solve problems, so they are not distracted by the calculations involved.
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.
Which of the following equations are represented by this part-part-whole model?
An image in a quiz
20 = 3 + 23
Correct answer: 23 = 20 + 3
Correct answer: 23 = 3 + 20
20 = 23 + 3
Q2.
Which part-part-whole model represents 49 = 40 + 9
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Q3.
The following equations are correct. True or False. 39 = 9 + 30, 39 - 30 = 9, 30 + 9 = 39 and 9 = 39 - 30
An image in a quiz
Correct answer: True
False
Q4.
Which of the following completes the equation correctly? 80 = - 4
Correct Answer: 84
Q5.
Use > , < or = to complete the equation
An image in a quiz
<
Correct answer: >
=
Q6.
Use > , < or = to complete the equation
An image in a quiz
Correct answer: <
>
=

6 Questions

Q1.
Which bar model matches this story? There were 43 bees in the hive. 40 of them flew away. How many were left?
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz
Q2.
Which problem does this bar model represent?
An image in a quiz
a
Correct answer: b
c
Q3.
What is the missing number?
An image in a quiz
Correct Answer: 56
Q4.
There are 37 children in the park. 7 children are wearing hats. How many children are not wearing hats? Which equation matches this problem?
37 + 7 = ?
Correct answer: 37 - 7 = ?
7 - 37 = ?
Q5.
Tick the problems that will use a subtraction to solve.
Correct Answer: An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
Q6.
Match the problem to the bar model.
An image in a quiz
Correct Answer:A,Laura had 60 shells. She found two more. How many does she have now?

Laura had 60 shells. She found two more. How many does she have now?

Correct Answer:B,Jun had 60 sticks. He lost 2 How many does he have left?

Jun had 60 sticks. He lost 2 How many does he have left?

Correct Answer:C,Andeep had 66 p. He spent 60 p on a pear. How much does he have left?

Andeep had 66 p. He spent 60 p on a pear. How much does he have left?