New
New
Year 2

Solve problems involving the addition of two-digit numbers

I can solve problems involving addition of two-digit numbers.

New
New
Year 2

Solve problems involving the addition of two-digit numbers

I can solve problems involving addition of two-digit numbers.

Lesson details

Key learning points

  1. Partitioning the addends can help us to solve problems involving two-digit numbers.
  2. Once we have written the equation, we must think carefully about the most efficient strategy to use.
  3. It is important to be able to calculate mentally before adding two 2-digit numbers.

Common misconception

When the amount of processing required for a task increases, children often default to inefficient strategies such as counting in ones if the use of efficient strategies are not yet automatic.

When solving problems, continue to focus upon, and discuss, the most efficient strategies to use to ensure that this thinking becomes automatic.

Keywords

  • Partition - To split a whole up into parts.

  • Efficient - Not wasting time or effort. An efficient strategy is one we can carry out easily.

Encourage children to 'think out loud' when solving problems and model this. Represent problems visually so the structure of them is fully understood, then focus on the numbers involved and how these can be used efficiently.
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.
Solve the equation in the most efficient way. 48 + 34 =
Correct Answer: 82
Q2.
Which of the following is correct?
27 + 35 = 52
62 + 29 = 81
Correct answer: 28 + 15 = 43
Q3.
Find the missing whole in the bar model. The missing whole is
An image in a quiz
Correct Answer: 92
Q4.
Which equation is represented by this number line?
An image in a quiz
10 + 3 + 4 = 17
Correct answer: 57 + 17 = 74
57 + 13 = 70
Q5.
Which of the following is the missing addend? + 36 = 51
An image in a quiz
87
Correct answer: 15
25
Q6.
Find the missing addend. 47+ = 73
Correct Answer: 26

6 Questions

Q1.
Solve the addition problem. Izzy has 34 beads on her bracelet and she adds 42 more. Use the strategy you find most efficient to solve the problem.
Correct Answer: 76
Q2.
Which strategy is the most efficient when solving this problem? There are 38 cows in the field and 57 in the barn. How many cows are there altogether?
Correct answer: Partition one addend
Partition both addends
Q3.
Which of the following is the most efficient way to solve this problem? There were 68 children in the hall, then 23 more children went in. How many children are in the hall now?
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
Q4.
Izzy sees 42 birds and Andeep sees 76 birds. How many more birds does Andeep see? How many tens will be in the missing addend when the equation is written for this problem?
2 tens
Correct answer: 3 tens
4 tens
Q5.
Izzy had 46 seeds in her packet and Andeep had 72 seeds in his packet. How many more seeds did Andeep have than Izzy?
Correct answer: 26
25
6
Q6.
Andeep counts 59 minibeasts and Izzy counts 83 minibeasts. How many more minibeasts does Andeep count?
Correct answer: 24
34
44