Short Blocks

# Maths Year 3/4 Autumn Addition & Subtraction (A)

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

## Strategies for adding and subtracting(suggested as 3 days)

### Planning and Activities

Day 1 Teaching
Use bar models to support writing addition and subtraction facts. Use number balances to model equalities; explore pairs to 13.
Further Teaching with Y4
Group Activities: T with Y4
Y3 -- Explore and write equalities (‘balancing’ sums).
Y4 -- Investigate ways in which digits can be arranged in an addition grid to give ascending totals, totals <100 and totals >100.

Day 2 Teaching
Use a 100 bead bar to demonstrate how 5 + 3 is similar to 15 + 3, 25 + 3, 35 + 3, …105 + 3, 125 + 3, 245 + 3, 845 + 3. Repeat for 17 + 7, 27 + 7, 37 + 7, 47 + 7, using ‘Target the 10’ strategy. Show on beaded, landmarked and empty number lines.
Group Activities: T with Y3
Y3 -- Identify mystery numbers by spotting patterns when adding 1-digit to 2-digit numbers.
Y4 -- Repeatedly add a 1-digit number to a 3-digit number; describe and explain any patterns in the ones digits.

Day 3 Teaching
Use the bead bar to show how 5 – 2 is similar to 15 – 2, 25 – 2, 35 – 2, 105 – 2, 145 – 2, 475 – 2. Repeat for 24 – 7, 34 – 7, etc. Show on beaded, landmarked and empty lines.
Group Activities: T with Y3
Y3 – Play a dice or card game to practise subtracting 1-digit from 2-digit numbers.
Y4 -- Dice game subtracting from 3-digit numbers.

### You Will Need

• Pairs to 12, sheets 1 and 2 (see resources)
• Number balance (or use an interactive version from e.g. www.nctm.org)
• 2-digit + 2-digit grid with missing totals (see resources)
• Mini-whiteboards and pens
• 0 to 100 beaded line (see resources)
• Additional activity sheets (see resources)
• 0 to 9 dice (or 1 to 10) and 1 to 9 cards
• Flipchart and pens

### Short Mental Workouts

Day 1
Addition facts for numbers 6 to 10

Day 2
Know by heart totals of any pair of 1-digit numbers

Day 3
Complements to multiples of 10

### Worksheets

Day 1
Y3: Write missing numbers in equalities.

Day 2
Y3: Add 1-digit to 2-digit numbers.
Y4: Add 1-digit to 3-digit numbers.

Day 3
Y3: Subtract 1-digit from a 2-digit-number.
Y4: Subtract 1-digit from a 3-digit-number.

### Mastery: Reasoning and Problem-Solving

Y3

• Write 4 number sentences to relate these three numbers: 13, 19 and 6.
• We know 13 + 7 = 20. So, what is 130 + 70?
We know 11 + 9 = 20. So, what is 110 + 90?
Repeat for two more pairs of numbers that total 20, then 200.

Y4

• Write 4 number sentences to relate these three numbers: 240, 390 and 150.
• Use a mental method to find:
150 + 50
35 + 65
192 + 6
66 + 29
153 + 39
200 – 52
240 + 550
73 – 25
630 – 150

In-depth Investigation
Use the games from the Day 3 group activities.

### Extra Support

Y3
Perfect Pairs

Using addition facts for 6, 7, 8, 9 and 10

Patterns Practice
Using addition fact to add single-digit numbers to 2-digit numbers, e.g. using 5 + 3 = 8 to work out 25 = 3 (not crossing 10s)

Y4