### Teaching and Group Activities for Understanding

**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.