Use a balanced equation to calculate unknown parts
Lesson details
Learning outcome
You can use a balanced equation to calculate unknown parts.
Key learning points
- I've added __ to this part so I need to subtract __ from the other part to keep the sum the same.
- I've subtracted __ from this part so I need to add __ to this part to keep the sum the same.
- A balance beam can represent equivalent expressions.
Keywords
Equation - An equation is used to show that one number, calculation or expression is equal to another.
Expression - An expression contains one or more values, where each value is separated by an operator. Two or more expressions with the same value can be separated by an equals sign to create an equation.
Whole - The whole is all the parts or everything, the total amount.
Part - A part is some of the whole.
Common misconception
Often, pupils understand the equals symbol to be a big reveal or a 'ta-da!' rather than a symbol denoting equivalence. This can make the idea of a balanced equation tricky.
Explore pupils' understanding of the equal sign at the start of the lesson. For children who still find it a tricky concept, make use of bucket scales and plasticine to explore equivalence.
Teacher tip
Many of the equations used here are the same template (provided that you use the commutative property of addition) 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.What is the missing part in this bar model?
Q2.327 − 98 =
Complete this mentally.
Q3.Jun buys two rugby balls which cost £7.98 each. How much does he spend altogether? Jun spends £
Q4.Sofia has £15 to spend. She buys a bat and ball set for £12.98 so how much change should she receive? Sofia should receive £ change.
Q5.Sam thinks of a 3-digit number and then adds 7 before dividing it by 4 to finish with the number 30
What was her starting number?
Q6.What is the missing whole in this bar model?
Assessment exit quiz
6 Questions
Q1.Which symbol can you insert between two expressions to show that they have the same value?
Q2.Which of the following are equations?
Q3.What is the mass of the plasticine part on the balance scales? g
Q4.Find the unknown by comparing parts.
32 + 27 = 30 +
Q5.Find the unknown by comparing parts.
0.25 + 0.67 = 0.29 +
Q6.Find the unknown by comparing parts.
23,000 + 15,000 = 21,750 +
To help you plan your 6 maths lesson on: Use a balanced equation to calculate unknown parts, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 6 maths lesson on: Use a balanced equation to calculate unknown 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.