Solve calculations with missing parts
Lesson details
Learning outcome
I can solve addition calculations with missing parts.
Key learning points
- The change in the sum is equal to the change in the missing addend.
- To calculate the missing addend, the known addend must be subtracted from the sum.
- A bar model can be used to represent a calculation with a missing addend.
Keywords
Equation - An equation is used to show that one number, calculation or expression is equal to another.
Unknown - An unknown is a quantity that has a set value but it is represented by a symbol or letter.
Whole - The whole is all the parts or everything, the total amount.
Part - A part is a piece or section of the whole.
Common misconception
The children might be inclined not to look at previous equations to help them. They might not make use of the adjustments to the whole.
Practise some really simple versions. Start with 1 + 2 = 3 and then ask them to adjust 3 by a single-digit number. Write this underneath and then ask them which part has changed and by how much? How do they know?
Teacher tip
The structure of the problems in these slides (provided that you use the commutative property of addition) is very similar so make use of the learning wall by drawing up comparison arrows and blank boxes so the structure is permanently on display.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Tick the equivalent expressions.
Q2.Tick the two numbers that are complements to 1,000
Q3.Tick the two numbers that are decimal complements to 10
Q4.What is the missing number in this equation?
+ 61 = 150
Q5.What is the missing number in this equation?
26 + + 11 = 70
Q6.What is the missing number in this equation?
+ 45 + 18 = 89 + 6
Assessment exit quiz
6 Questions
Q1.Which of the following best describes an unknown?
Q2.What is the mass of the plasticine on the balance scale?
Q3.What is the mass of the plasticine on the balance scale?
Q4.Without using a written method, calculate the unknown value in the pair of equations shown.
Q5.Without using a written method, calculate the unknown.
Q6.Without using a written method, calculate the unknown value in the pair of equations shown.
To help you plan your 6 maths lesson on: Solve calculations with missing parts, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 6 maths lesson on: Solve calculations with missing parts, 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 2 maths lessons from the Use equivalence and compensation to simplify and solve addition calculations unit, dive into the full primary maths curriculum, or learn more about lesson planning.