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

An expression contains one or more terms or numbers, where each term or number is separated by and operator but an expression does not have an equals sign.

Explain how to balance equations with addition and subtraction expressions

Maths

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.

Calculating using knowledge of equivalence in addition and subtraction

Match each addition expression to an equal subtraction expression.

What is the missing addend needed to balance this equation? 48,000 + {{ }} = 71,000 − 15,000  

What is the missing subtrahend to balance this equation? 52,000 + 9,000 = 79,000 − {{ }}  

This equation is unbalanced. 65,000 − 8,000 = 18,000 + 38,000     How can you change 18,000 in the addition expression to balance the equation?

This equation is unbalanced. 55,500 −  8,000 = 22,250 + 26,250     What should the subtrahend be to balance this equation?

Round 8,907 to the nearest multiple of 10

Which of the following expressions has the same difference as 150 − 30? Can you reason without calculating?

Use an efficient strategy to calculate 27,648 + 32,963 = {{ }}

Use an efficient strategy to calculate 10 − 7.452 = {{ }}

What is 8.96 when rounded to the nearest whole number?

Use an efficient strategy to calculate the unknown value g in  g − 1,508  = 4,650 − 1,600

This lesson will soon be taken down.

Explain how to balance equations with addition and subtraction expressions

Lesson outcome