Find the missing addend when adding two-digit numbers
Lesson details
Learning outcome
I can find the missing addends when adding two-digit numbers.
Key learning points
- Two-digit numbers can be partitioned to help find a missing digit or a missing addend.
- One equation can be used to help solve another equation.
- The patterns in equations can be used to help find a missing addend.
Keywords
Addend - Any of the numbers that are added together.
Digit - A single symbol used to make a numeral.
Common misconception
When finding a missing ones digit in an addend, children may confuse the tens and ones digits in the sum, thus adding to the ones to make the amount of the tens digit or vice versa.
Partition the addends into tens and ones so the place value of the digit that is missing is clear.
Teacher tip
Begin working practically with Base 10 blocks to help visualise the equation. Check the movement of the blocks when exploring equivalent expressions. Encourage children to mentally manipulate numbers by predicting equivalent calculations before checking.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Match the expressions which will have the same sum.
53 + 42
63 + 21
71 + 22
Q2. Which expression will have the same sum as 14 + 53?
Q3.Which equation will have a sum in the fifties?
Q4.Which equation will have a greater sum than 25 + 61 = ?
Q5.40 + + 5 + 3 = 43 + 25
Q6.67 + 21 = 88, so 61 + 27 =
Assessment exit quiz
6 Questions
Q1.Which digit is missing in this equation?
Q2.Which of the following is the missing addend?
Q3.Use the first equation to help solve the second equation.
Q4.Which of the following cannot be one of the tens digits in the equation?
Q5.One of the Base 10 blocks has been moved over from one addend to the other. Which of the following could show the new equation? Tick two.
Q6.Find the missing addend.
To help you plan your 2 maths lesson on: Find the missing addend when adding two-digit numbers, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 2 maths lesson on: Find the missing addend when adding two-digit numbers, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 1 maths lessons from the Addition and subtraction of two 2-digit numbers unit, dive into the full primary maths curriculum, or learn more about lesson planning.