Short Blocks

# Maths Year 4 Autumn Addition and Subtraction (B)

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

## Mentally add/subtract near multiples(suggested as 2 days)

### Planning and Activities

Day 1 Teaching
Demonstrate using an empty number line to add 40 to 356. Use the same empty number line to model adding 41 and then 39. Show how the empty number line is useful when we add near multiples. Children use the same process to add 50 and 49 to 736. They then add 200, 199 and 201 to 358.
Group Activities
-- Make up word problems involving adding multiples and near multiples of 10 or 100 to a 3-digit number.
-- Add multiples and near multiples of 10 or 100 to a 3-digit number where the answer is more than 1000.

Day 2 Teaching
Ask children to show 385 – 50 on an empty number line on their whiteboards. What happens if we subtract 51, not 50? Children draw a hop back to 334, label it – 1, and label 334. How do we subtract 49 not 50? Draw a hop labelled + 1 to 336. Make sure that children are clear about which way to adjust. Repeat to subtract 200, 201 and 199 from 645.
Group Activities
Use the in-depth problem-solving investigation ‘Images of Addition and Subtraction’ from NCETM as today’s group activity.
Or, use these activities:
-- Use an empty number line to subtract near multiples of 10 and 100 from 3-digit numbers.

### You Will Need

• ‘Word Problems’ sheet (see resources)
• Whiteboards
• ‘Spinners’ sheets 1 to 3 (see resources)
• Paperclips

### Mental/Oral Maths Starters

Day 1
Adding multiples of 10 (pre-requisite skills)

Suggested for Day 2
6 times table (simmering skills)

or

Suggested for Day 2
8 times table (simmering skills)

### Worksheets

Day 1
Add multiples and near multiples of 10 and 100 to 3-digit numbers.

Day 2
Subtract multiples and near multiples of 10 and 100 from 3-digit numbers.

### Mastery: Reasoning and Problem-Solving

• Complete this sequence by adding 198 each time.
169, 367, ___, 763, ___, ___
• What needs to be subtracted from 985 to get 587?
• Harry subtracted 59 from 354 and got 293. Explain what he did wrong.
• Complete the number sentences:
438 + 39 = ___
356 – ___ = 307
___ – 198 = 314

In-depth Investigation: Images of Addition and Subtraction
This activity looks at a range of models and images used for addition and subtraction. Challenge the children to sort the cards and think about all the skills they are using. Images of Addition and Subtraction from ncetm.org.uk

### Extra Support

Swapping Digits
Adding and subtracting 1s, 10s, 100s to/from 3-digit numbers