Short Blocks

Maths Year 5 Spring Multiplication and Division

Each unit has everything you need to teach a set of related skills and concepts.

Multiples & factors; mental x/÷ strategies (suggested as 3 days)

Planning and Activities

Day 1 Teaching
Use the ITP Number grid to highlight multiples of 2 and 3. Point out that 6 is the lowest common multiple of 2 and 3. Repeat for LCM of 3 and 4, then of 3 and 6, then 6 and 9. Now find highest common factor of 32, 16 and 24, then 12, 20 and 32.
Group Activities
Use the ‘LCM Squares’ in-depth problem-solving investigation below as today’s group activity.
Or, use this activity:
-- Derive highest common factors and/or lowest common multiples.

Day 2 Teaching
Write 23 × 10 and 23 × 5 and show how we can use the former to solve the latter – it’s a lot more efficient than counting in 5s! Repeat for 23 × 20 and 23 × 19. Then model 23 × 6 as 23 × 3 doubled. Discuss strategies for 23 × 8 by repeated doubling.
Group Activities
-- Explore mental methods based on doubling and halving to multiply by 5, 20, 6, 4 and 8.

Day 3 Teaching
Use 240 ÷ 10 to solve 240 ÷ 5 and 240 ÷ 20. Ensure children realise when they need to double to give a bigger answer (÷5) and when they need to halve it to give a smaller answer (÷20). Ask children to work out 270 ÷ 3, and use this to find 270 ÷ 6. Use repeated halving to divide by 4 and 8.
Group Activities
-- Explore mental strategies to divide by 5, 20, 6, 4 and 8. Articulate strategies to make generalisations.

You Will Need

Mental/Oral Maths Starters

Day 1
Divisibility by 2, 3 or 5 (pre-requisite skills)
Click on Random Number Bingo Generator from www.primaryresources.co.uk

Suggested for Day 2
Double 2-digit numbers (simmering skills)

Suggested for Day 3
‘Fizz-Buzz-Whizz: Common multiples’ (simmering skills)

Worksheets

Day 1
Finding highest common factor and lowest common multiple of sets of numbers.

Day 2
Using mental strategies (in particular doubling and halving) to multiply by 5, 20, 6, 4 and 8.

Day 3
Using mental strategies (in particular doubling and halving) to divide by 5, 20, 6, 4 and 8; articulate strategies.

Mastery: Reasoning and Problem-Solving

  • Is the lowest common multiple of 6 and 4 smaller than the highest common factor of 30 and 45?
  • Write common factors of 24 and 48.
    Write common multiples of 3 and 5 up to 60.
    Are any numbers in both sets?
  • True or false?
    There are exactly four 2-digit, common multiples of 3 and 7.
    4 and 5 are common factors of all 2-digit multiples of 10.
    15 is a factor of 100.
  • If 350 ÷ 5 is 70, calculate 350 ÷ 10, 350 ÷ 20 and 350 ÷ 70.
    So can you have a try at 350 ÷ 2.5?


In-depth Investigation: LCM Squares
Children use trial and improvement to find the smallest possible total on a square of lowest common multiples.

Extra Support

Mammoth Multiplications
Using known times tables and place value to multiply, e.g. 4 × 3, 4 × 30, 4 × 300.