lesson
Make equal-sized pieces first
1 · Learn
To add 1/4 and 3/8, rewrite the quarter as two eighths. Then 2/8 + 3/8 = 5/8.
For subtraction, use the same idea. You cannot subtract counts of differently sized pieces as though their sizes matched. A bar model helps show why the equivalent fraction is needed.
2 · Worked example
For 5/6 − 1/3, change 1/3 to 2/6. Three sixths remain, equivalent to one half.
3 · Your turn
Calculate 3/4 + 5/8 and 7/10 − 1/5.
Check your answer
11/8, or 1 and 3/8; 5/10, or 1/2.
4 · Apply your learning
Draw fraction bars for both calculations and label the shared denominator before combining parts.
Adult guidance and safety
Model the calculation or measurement before relying on a procedure. Explain estimates, units and checks. Use a ruler/protractor and suitable diagrams where needed; text examples alone do not establish practical skill or fluency.
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Check a calculation · Year 5 onward
Use this only when your teacher or adult allows a calculator for the task. Show your thinking first. It does not replace mental or written arithmetic and does not mark your lesson answer.
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