Times tables revision: factors & multiples

Maths Year 4
This unit is part of Year 4 Flexible Maths Blocks Multiplication and Division and Year 4 Maths Planning Multiplication and Division (A)

Planning and Activities

Day 1 Teaching
Launch ITP ‘Number dials’. Randomise the central number and multipliers. Click on an outside number. What times table do you think it might be? What else could it be? What can't it be? Why? Reveal another product. Carry on until children all agree. Repeat.
Group Activities
-- Complete a multiplication grid up to 12 × 12.
-- Explore the calculations on a 12 × 12 multiplication grid that children often find harder to remember.

Day 2 Teaching
Sketch 24 counters arranged in a 6 by 4 array. What other arrays are possible using 24 counters? Each child sketches a different way on their whiteboard. Share ideas. Say that 24 is a multiple of 1, 2, 3, 4, 6, 8, 12 and 24. Explain that these are its factors. Write factors of 21 then of 16.
Group Activities
-- Investigate the factors of numbers up to 40.

Day 3 Teaching
Show children an Interactive Whiteboard multiplication grid. Look at the number 16. Where does it appear on the grid? It is in the 2 times table and in the 8 times table. It is also in the 4 times table. Write its pairs of factors. Some numbers on the grid only have 2 factors, other than themselves and 1, e.g. 21 has 3 and 7. This is why it only occurs twice on the grid. It is only in two tables, the 3 times and the 7 times tables. Repeat for 44. Introduce into the whole class investigation.
Group Activities
Use the in-depth problem-solving investigation ‘Shape Times Shape’ from NRICH as today’s group activity.
Or, use this activity:
-- Explore the factors of numbers that occur multiple times on a multiplication grid.

You Will Need

  • ITP ‘Number dials
  • Flipchart, whiteboards and pens
  • ‘12 × 12 Multiplication grid’ (see resources)
  • ‘Partially completed multiplication grid’ (see resources)
  • Cubes, counters and 0 - 9 dice
  • Interactive Whiteboard multiplication grid
  • ‘Highlighted 12 × 12 multiplication grid’ (see resources)

Mental/Oral Maths Starters

Day 1
7 times table (pre-requisite skills)

Day 2
9 times table (pre-requisite skills)

Suggested for Day 3
Telling times to the next hour (simmering skills)

Worksheets

Day 1
Identify missing numbers on a multiplication grid.

Day 2
Match numbers to lists of factors.

Day 3
Identify all the factors of given numbers.

Mastery: Reasoning and Problem-Solving

  • Selma says ‘The bigger a number, the more pairs of factors it has’. Do you agree with her? Explain your ideas.
  • What one number does the letter ‘a’ stand for in each of these number sentences?
    a × 6 = a + 40
    7 × a = 60 take away ½ of a.
  • Always true, sometimes true or never true?
    A number with only two factors is odd.
    A number with 4 factors is even.
    A number less than 100 with 6 factors is even.
    A number with 6 as one of its factors, also has 3 as a factor.
    An odd number can have 2 as a factor.

In-depth Investigation: Shape Times Shape
Eleven different shapes each stand for a different number. Children use the multiplication calculations to work out what they are. Shape Times Shape from nrich.maths.org.