Multiply 1-digit numbers by decimals
Lesson details
Learning outcome
I can explain how to use multiplying and dividing by 10 or 100 to multiply 1-digit numbers by decimal fractions.
Key learning points
- Use place value to convert the decimal fraction by multiplication to a whole number.
- Use unitising, known facts and/or the distributive law to multiply the whole numbers.
- Use place value to convert the number by division to adjust the product.
Keywords
Unitising - Treating groups that contain the same number of things as ‘ones’ or ‘units’. It is important particularly in handling money and in understanding place value and supports us to think multiplicatively.
Distributive law - The distributive law says that multiplying a number by a group of numbers added together is the same as doing each multiplication separately.
Common misconception
Children may scale the decimal fraction inaccurately or may forget to scale the product accordingly to solve the original equation.
If a decimal fraction has only tenths, we multiply by 10 to form a whole number. If the decimal fraction has hundredths, we multiply by 100 to form a whole number. Remember to adjust the product to answer the original equation.
Teacher tip
Provide scaffolds for those who are not confident with their times tables to avoid overload. Children should already be aware of the distributive law but it may be an idea to revisit this prior to the lesson to ensure children are confident with the concept. Stick to mental methods of calculation.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Count up in 25s. What would come next? 25, 50,
Q2.Match the factors to their product.
30
140
1030
21
5
Q3.Match the expressions to their answer.
4
15
1.5
0.4
0.04
Q4.Match the equivalent expressions.
53 ÷ 10
53 ÷ 100
53 ÷ 1
5.3 ÷ 10
5.3 ÷ 100
Q5.Lucas has 1.8 kg flour. Sofia has one-tenth times this amount. How much flour does Sofia have? kg
Q6.Sofia’s flower is 87 cm tall. Lucas’ has only grown to one-hundredth times this height. How tall is Lucas’ flower? cm
Assessment exit quiz
6 Questions
Q1.If 9 × 14 = 126, what does 9 × 1.4 equal?
Q2.Calculate 9 × 2.5 =
Q3.Use unitising and known facts to match the equation to its product.
0.32
0.42
4.5
1.2
2.4
Q4.Calculate this: 3 × 8.7 =
Q5.Plums cost £2.35 per kilogram. Sofia buys 4 kilograms of strawberries. How much does she spend? £
Q6.Sofia buys eight stickers. They cost £0.52 each. How much do they cost altogether? £
To help you plan your 5 maths lesson on: Multiply 1-digit numbers by decimals, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 5 maths lesson on: Multiply 1-digit numbers by decimals, 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 Calculating with decimal fractions unit, dive into the full primary maths curriculum, or learn more about lesson planning.