Short Blocks

# Maths Year 3 Summer Addition & Subtraction (B)

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

## Add/subt multiples of 10, near multiples(suggested as 3 days)

### Planning and Activities

Day 1 Teaching
Write 346 + 50. Which digit will change? Confirm it is just the 10s digit; model counting on in 10s from 346 to answer. Repeat with 231 + 30 and 636 + 20.
Write 376 + 50: Which digit will change? Count on in 10s to show how both 100s & 10s digits change. Repeat for 346 + 500, 336 – 50 and 846 – 500.
Group Activities
-- Solve addition or subtraction word problems by counting on or back in 1s, 10s or 100s; cross multiples of 10 and 100.
-- Make up calculations that result in the 10s and/or the 100s digit changing.

Day 2 Teaching
Show a grid from 301 to 400. Demonstrate adding or subtracting 10s by moving up or down the grid. What happens when we add a ‘nearly number’ like 39 instead of 40? We need to add 40, then adjust by subtracting 1. Repeat for adding and subtracting other nearly numbers, e.g. 356 + 41, 356 + 39, 356 – 39, 382 – 59, 338 + 29.
Group Activities
-- Add and subtract near multiples to 3-digit numbers with the same 1s digit.

Day 3 Teaching
Display ‘Word problems’ one at a time; ask children to work on them in pairs. Think carefully about the maths that is needed – write a number sentence; then answer the question. Discuss their thoughts and clarify any misunderstandings as you work through each question. Choose one of the following to create a new word problem: 268 + 30, 583 – 40, 355 + 200, 632 – 400, 346 + 19, 475 – 21.
Group Activities
Use the in-depth problem-solving investigation ‘Place value puzzles’ as today’s group activity.
Or, use these activities:
-- Solve word problems by adding or subtracting multiples, or near multiples, of 10 and 100.
-- Use spinners to create word problems involving adding or subtracting multiples, or near multiples, of 10 and 100.

### You Will Need

• ‘Word problems’ sheet 1 (see resources)
• ‘Addition and subtraction word problems’ sheets 1 and 2 (see resources)
• Whiteboards and pens
• ‘Adding and subtracting multiples of 10 and 100’ (see resources)
• ‘301-400 grid’ (see resources)
• ‘Number cards’ Set A and B (see resources)
• ‘1-100 grid’ (see resources)
• Additional activity sheets (see resources)

### Mental/Oral Maths Starters

Day 1
Count on in steps of 10 and 100 from 3-digit numbers (pre-requisite skills)

Day 2
Count back in steps of 10 and 100 from 3-digit numbers (pre-requisite skills)

Suggested for Day 3
Revise the 3 times table (simmering skills)

### Worksheets

Day 1
Solve word problems by counting on or back in 10s or 100s from 2-digit and 3-digit numbers.

Day 2
Add and subtract near multiples of 10 from 2-digit and 3-digit numbers.

Day 3
Create word problems for addition and subtraction of multiples of 10s and 100s and near multiples of 10.

### Mastery: Reasoning and Problem-Solving

• Add 40 to each of…
216, 159, 608
• Subtract 50 from each of…
117, 349, 608
• Complete each pair of calculations:
 436 + 40 = 436 + 39 = 573 - 30 = 573 - 29 = 773 - 40 = 773 - 41 = 105 + 51 = 105 + 49 =
• Solve these word problems:
-- Sam’s Dad buys a laptop for £345. Sam buys a game for £39. How much did they spend in total?
-- Bella has measured the shelf and it is 253cm long. She saws off two pieces that are each 29cm long. How long is the shelf now?

In-depth Investigation: Place Value Puzzles
Solve the place value subtraction puzzles.

### Extra Support

This unit has no additional Extra Support activity.