An unknown is a quantity that has a set value but it is represented by a symbol or letter.

An equation is used to show that one number, calculation or expression is equal to another.

An expression contains one or more values, where each value is separated by an operator.

Explain how to balance equations with subtraction expressions

Maths

Explain how to balance equations with addition expressions

Explain how to balance equations with addition or subtraction expressions

Explain how to balance equations with addition and subtraction expressions

Use knowledge of balancing equations to solve problems

In this unit pupils will explain how to balance equations with addition or subtraction expressions and use their knowledge of balancing equations to solve problems. In the future unit pupils will compare and represent the structure of problems with two unknowns using a bar model. They will systematically solve problems with two unknowns using trial and improvement.

In the prior unit pupils explained how increasing or decreasing the minuend affected the difference. They used known facts to explain how adjusting the minuend made mental calculation easier. In this unit pupils will explain how to balance equations with addition or subtraction expressions and use their knowledge of balancing equations to solve problems.

In this unit pupils will explain how to balance equations with addition or subtraction expressions and use their knowledge of balancing equations to solve problems.

Calculating using knowledge of equivalence in addition and subtraction

Select the correct symbol to compare the expressions. 40.36 − 21.63 ___ 39.86 − 27.91

Select the correct symbol to compare the expressions. 12,453 − 6,104 ___ 27,896 − 19,317

The unknown subtrahend in the diagram below is {{ }}

Use an efficient strategy to calculate the unknown value g in  g − 26,100  = 47,865 − 28,300

Use an efficient strategy to calculate the unknown value g in 46.5 − 12.6 = 107.9 − g

Izzy begins with 350 g of plasticine and removes 125 g. Jun begins with an unknown mass of plasticine and removes 90 g. Now they have the same mass of plasticine. How much did Jun begin with? {{ }} g

Which of the following expressions has the same sum as 306 + 30? Can you reason without calculating?

Round 23,654 to the nearest multiple of 10

Use an efficient strategy to calculate 56.75 + 22.25 = {{ }}

Use the correct inequality symbol to make this correct: 349,207 {{ }} 349,086

Use rounding, estimating, comparing or reasoning to determine the missing symbol in this inequality statement. 36 + 23 {{ }} 23 + 47

Use an efficient strategy to calculate 10,000 − 8,655 = {{ }}

Explain how to balance equations with subtraction expressions

Lesson outcome