# Maths Year 3 Summer Addition & Subtraction (A)

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

## Mentally add/subtract 1-digit numbers (suggested as 2 days)

### Mastery

### Worksheets

### Resources

### Extra Support

### Teacher Tips

## 3-digit expanded and compact addition (suggested as 5 days)

### Planning and Activities

**Day 1 Teaching**

Write 654 + 567. One child calculates answer using expanded addition, another using compact addition. Remind both children to leave a space before drawing the lines for the answer. When children have finished, compare their workings and answers. Write 478 + 245, and 837 + 367. Use your preferred strategy to calculate the two answers.**Group Activities**

-- Add two 3-digit numbers, using expanded and compact addition methods.

-- Make two 3-digit numbers using dice. Then add the numbers using compact addition.

**Day 2 Teaching**

Write 426 + 217, 742 + 276 and 587 + 278. Children round each to nearest 100, then add to estimate the total. Repeat, this time children round each to nearest multiple of 10; then use addition of 2-digit numbers to estimate total. Give 1 addition to each third of the class to find an exact answer. Compare with estimates.**Group Activities**

-- Think mathematically to use chosen digits to make two (or three) 3-digit numbers with a total as close as possible to 600 (or 1000). Use compact addition.

-- Estimate the total of two 3-digit numbers; find the exact total using compact addition.

**Day 3 Teaching**

Write 48 + 26 + 35. Agree we could do this by adding the larger two numbers (83) and then the smallest. BUT we can also use column addition. This is especially useful if we are adding four 2-digit numbers. Model both expanded and compact addition for 45 + 28 + 63 + 38. Here, we had an extra 20 to add to the 10s! Children have a go with 36 + 45 + 58 + 23.**Group Activities**

-- Add three or four 2-digit numbers, using expanded and compact addition methods.

-- Estimate the total when adding three or four 2-digit numbers, then find the answer using compact addition.

**Day 4 Teaching**

Write 43, 86, 27, 36, 18, 54, 72 and 67. Look for 3 numbers that might have a total close to 100. They check using column addition. How did you choose your numbers? Rounding to the nearest 10 can help. Now choose 3 numbers with a total near 150. Check using column addition. Now choose 4 numbers with a total near 150.

Group Activities

-- Look for 3 or 4 numbers that children estimate will have a total near given multiples of 10.

-- Play ‘missing digits’. Children work out the missing 1s digit in addition calculations.

**Day 5 Teaching**

Add 3 numbers where the digits in each number are the same, e.g. 33 + 44 +55. Share answers; discuss observations. Ask them to choose other trios of similar numbers to check if this is always the case. Can we write a ‘rule’ to describe what happens with additions like these? If one doesn’t work, check! [If the answer is a 3-digit number, the middle digit is the sum of the two digits on either side - a function of this being one of a certain group of multiples of 11; If the answer is a 2-digit number, both digits are the same].**Group Activities**

Use the in-depth, whole-class, problem-solving investigation– Investigating 11– as today’s group activity.

-- Investigate patterns when adding three or four 2-digit numbers that have a difference of 11, e.g. 89+ 78 + 67.

### You Will Need

- Whiteboards and pens
- 3-digit number cards (
*see resources*) - 2-digit number cards (
*see resources*) - Calculators
- 0 – 9 Dice
- Counters
- 0-9 cards
- 100s, 10s and 1s place value cards
- 2-digit number cards
- ‘Addition’ sheets 1 and 2 (
*see resources*) - ‘Estimating totals’ sheets 1 to 3 (
*see resources*) - ITP: Spinners

### Mental/Oral Maths Starters

**Day 1**

Know total of any pair of single-digit numbers (*pre-requisite skills*)

**Day 2**

Round 3-digit numbers to nearest 10 and 100 (*pre-requisite skills*)

**Day 3**

Add 4 single-digit numbers (*pre-requisite skills*)

**Day 4**

Add multiples of 10 (*pre-requisite skills*)

**Suggested Day 5**

Subtract single-digit numbers (*simmering skills*)

### Worksheets

**Day 1**

Use expanded or compact addition to add two 3-digit numbers.

**Day 2**

Choose two 3-digit numbers from those given to target one of several given target numbers. Estimate and find exact totals.

**Day 3**

Use expanded or compact addition to add 3 or four 2-digit numbers.

**Day 4**

Choose three 2-digit numbers from those given to target one of several given target numbers. Estimate and find exact totals.

**Day 5**

Add 3 or four 2-digit numbers using compact addition.

### Mastery: Reasoning and Problem-Solving

- Choose a different method to solve each addition:

375 + 567 =

638 + 51 =

24 + 36 + 25 = - Use column addition to help you to find each missing number:

548 + 175 = ☐

☐ – 356 = 387

635 + 296 = ☐

☐ – 466 = 247 - Sally has 45 Pokémon cards, Bill has 67, Jon has 28 and Parvati has 86. How many do they have altogether?
- Choose four of these numbers likely to give a total close to 200:

73 68 56 75 66 37

Add them using column addition. Is the closest possible total to 200?

**In-depth Investigation: Investigating 11**Look for patterns when adding numbers with a difference of 11. See Day 5 group activity 1 for details.

### Extra Support

**Totally Investigative**

Adding any pairs of 2-digit numbers using partitioning (including 1s> 10 AND 10s > 100)

## Revise expanded and column addition (suggested as 4 days)

### Planning and Activities

**Day 1 Teaching**

Demonstrate both expanded & compact written addition: 46 + 27 + 52 + 17. Remind children to leave a space above the answer for ‘carry’ digits.

Write 82 + 32 + 47 + 25. How could we estimate the answer? Recall strategy to round each number to the nearest 10, then add these multiples of 10. Agree estimates, then use expanded or compact addition to find exact answer. Repeat for 63 + 18 + 36 + 55.**Group Activities**

Use the ‘Mobile Towers’ in-depth problem-solving investigation below as today’s group activity.

Or, use these activities:

-- Revise estimating totals and adding three or four 2-digit numbers using compact addition.

-- Estimate the total of four 2-digit numbers; find exact totals using column addition.

**Day 2 Teaching**

Write 378 + 123 + 285. Ask children to estimate the answer by rounding to nearest 100. Check estimate using first expanded column addition then compact. Remind children to leave a line above the answer. Repeat for 416 + 389 + 534.

**Group Activities**

-- Practise adding trios of 3-digit numbers, using either expanded or compact addition. Totals <1000 and >1000.

-- Estimate, then calculate, three costs that add up to <£1000.

**Day 3 Teaching**

Record expanded addition for £3.55 + £2.26. Demonstrate how we add the 1ps, the 10ps, the pounds and then add the 3 amounts together. Repeat with £4.72 + £2.54 pointing out what happens when you add 70p and 50p – a total more than £1. Children have a go at £4.59 + £2.25 and £4.72 + £3.59, choosing to use expanded or compact addition.**Group Activities**

-- Practise using expanded or compact addition to add amounts of money.

-- Estimate then calculate multiple costs that add up to under £10.

**Day 4 Teaching**

Show four holiday items with prices £2.74, £1.43, £8.53 and £5.72. Choose two to buy for less than £5. Find their total, then calculate the change from £5 using Frog. Repeat to choose two for less than £10 & find change. Repeat for a pair under £20.**Group Activities**

-- Choose two items that add up to under £5, £10 or £20 then calculate change.

-- Buy multiple items that add up to under £20, then calculate change.

### You Will Need

- Whiteboards and pens
- Cards with 2 digit numbers on them
- ‘Adding three 3-digit numbers’ sheets 1, 2 and 3 (see resources)
- ‘Bicycles for sale’ sheet (see resources)
- ‘Adding amounts of money’ sheets 1 and 2 (see resources)
- Books with price tags £4.79, £3.14, £6.01, £5.49, £5.88, £5.25, £3.23, £4.65, £4.29, £2.35, £5.17, £2.52
- Items that might be for sale in a seaside shop e.g. sun cream, beach towel, bucket, spade with prices £2.74, £1.43, £8.53 and £5.72
- ‘The beach shop’ sheet (see resources)
- Coins and dice

### Mental/Oral Maths Starters

**Day 1**

Round 3-digit numbers to nearest 100 (*pre-requisite skills*)

**Day 2**

Round amounts of money to the nearest pound (*pre-requisite skills*)

**Day 3**

Say the amount needed to make £1 (*pre-requisite skills*)

**Suggested for Day 4**

Add 3 multiples of 10 (*simmering skills*)

### Worksheets

**Day 1**

Round 2-digit numbers to the nearest 10; choose three or four of them to add up to approximate one of several target numbers.

**Day 2**

Round 3-digit numbers to the nearest 10; choose two or three of them to add up to approximate one of several target numbers.

**Day 3**

Round to the nearest pound to estimate each total. Then use column addition to ﬁnd the exact answer.

**Day 4**

Calculate the price of 2 items, and then the change from £5, £10 or £20.

### Mastery: Reasoning and Problem-Solving

- Choose three of these numbers and write an estimate of their total:

475 386 287 349 248

Add the three numbers and compare the actual answer with your estimate. Repeat, choosing three different numbers. Was your second estimate closer? - Work out the missing numbers in this addition puzzle:

£4 ☐p 8p__£7 80p ☐p__

£☐ 60p 1p

**In-depth Investigation: Mobile Towers**Children create 4 or five 2-digit numbers and add these to get different totals.

### Extra Support

**Addition of Three-digit Numbers **

Using the interactive tool from Harcourt School at http://www.harcourtschool.com, children use base-10 blocks to explore regrouping in addition