Explain how to solve problems where the percentage part and size is known but the whole is unknown
Lesson details
Learning outcome
I can solve problems where a percentage part is known but the whole is unknown.
Key learning points
- If I know about a part, I can work out the whole from that part.
- If I know what 10% is, I can multiply by 10 to calculate 100%.
- If the part is a factor of 100, I can multiply the part by the other factor to calculate the whole.
Keywords
Percentage - A percentage is a proportion of a whole.
Common misconception
Pupils may not always instantly recognise that a percentage part is a factor of 100
Discuss factors of 100 with the pupils, for example, as factor pairs. Allow them to keep these displayed to refer to throughout the lesson if needed to help make this connection.
Teacher tip
To access this lesson, pupils must have familiarity with working out percentages of numbers. Pupils may find bar models and ratio tables helpful. Bar models help in understanding the structure of each problem. Ratio tables help in clearly setting the information out to see what needs calculating.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.If 100% of an amount is 320 km, find these percentages.
Q2.10% of a race is 1.5 km Calculate these percentages of the race.
Q3.Aisha’s battery has 61% of 600 minutes left. Complete each step of the table to calculate 61% of 600 minutes. minutes
Q4.Lucas needs to find the number of children who cycled to school. Look at the pie chart and complete each step of the table to calculate 21% of 400 children
Q5.Look at the table and find the missing percentage. 18 = % of 60
Q6.Use the table to calculate the missing percentage. 440 = % of 800
Assessment exit quiz
6 Questions
Q1.If I know a part, I can work out the whole. Match the parts of the sentence correctly.
Q2.Lucas has read 25% of his book. He has read 64 pages. His book is pages long.
Q3.Aisha thinks of a number. 20% of her number is 104 What is her number?
Q4.Lucas has read 75% of his book. This is 90 pages. How many pages are in his book? pages
Q5.Aisha thinks of a number. 40% of her number is 72 What number is Aisha thinking of?
Q6.Lucas takes part in a race. He has run 30% of the race which is 600 m What is the distance of the whole race? m
To help you plan your 6 maths lesson on: Explain how to solve problems where the percentage part and size is known but the whole is unknown, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 6 maths lesson on: Explain how to solve problems where the percentage part and size is known but the whole is unknown, 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 Understanding percentages unit, dive into the full primary maths curriculum, or learn more about lesson planning.