Addition and Subtraction Partitioning and column addition Objectives

Addition and Subtraction Partitioning and column addition Objectives Day 1 Add pairs of 2 -digit numbers mentally. Add 2 -digit numbers to 3 -digit numbers using mental strategies. Day 2 Add two 3 -digit numbers using compact written addition. Day 3 Add three 3 -digit numbers using compact written addition. © hamilton-trust. org. uk 1 Year 4

Addition and Subtraction Partitioning and column addition Starters Day 1 Place value in 4 -digit and 5 -digit numbers (pre-requisite skills) Suggested for Day 2 Count in 1/4 s and 1/8 s (simmering skills) Suggested for Day 3 Addition facts to 20 (simmering skills) © hamilton-trust. org. uk 2 Year 4

Addition and Subtraction Partitioning and column addition Starter Place value in 4 -digit and 5 -digit numbers © hamilton-trust. org. uk 3 Year 4

Addition and Subtraction Partitioning and column addition Starter Count in 1/4 s and 1/8 s © hamilton-trust. org. uk 4 Year 4

Addition and Subtraction Partitioning and column addition Starter Addition facts to 20 © hamilton-trust. org. uk 5 Year 4

Addition and Subtraction Partitioning and column addition Objectives Day 1 Add pairs of 2 -digit numbers mentally. Add 2 -digit numbers to 3 -digit numbers using mental strategies. © hamilton-trust. org. uk 6 Year 4

Day 1: Add pairs of 2 -digit numbers mentally. Add 2 -digit numbers to 3 -digit numbers using mental strategies. Let’s remember how to add 2 numbers by partitioning. Partition the numbers into 10 s and 1 s. Add the 10 s, then the 1 s. Then add together to find the total. © hamilton-trust. org. uk + 2 04 4 08 8 2 0 4 4 0 2 0 + 4 0 = 6 0 = 1 02 + 4 8 + 1 02 6 0 7 = 7 02 Year 4

Day 1: Add pairs of 2 -digit numbers mentally. Add 2 -digit numbers to 3 -digit numbers using mental strategies. Let’s try 178 + 31. Let’s see how to add a 2 -digit number to a 3 -digit number. First partition the numbers: 178 = 100 + 70 + 8 and 31 = 30 + 1 Then re-order the 10 s and 1 s and add: 178 + 31 = 100 + 70 + 30 + 8 + 1 = 100 + 9 = 209 © hamilton-trust. org. uk It’s O. K. to do some jottings to help! 8 Year 4

Day 1: Add pairs of 2 -digit numbers mentally. Add 2 -digit numbers to 3 -digit numbers using mental strategies. Now look at these 4 questions: 125 + 26 154 + 27 22 + 195 What do you think is the most efficient strategy for each? e. g. For 137 + 19 you can add 20 and subtract 1. Talk to your partner… How would you do each one? Try with some jottings. © hamilton-trust. org. uk 137 + 19 9 Year 4

Challenge © hamilton-trust. org. uk 10 Year 4

Addition and Subtraction Partitioning and column addition Objectives Day 2 Add two 3 -digit numbers using compact written addition. © hamilton-trust. org. uk 11 Year 4

Day 2: Add two 3 -digit numbers using compact written addition. Try 324 + 439 on your whiteboards using the compact written method. 324 + 439 1 3 324 + 439 1 63 Set the numbers out with 100 s, 10 s and 1 s lined up. Don’t forget the space above the line for any 10 s digits from adding 1 s or 100 s digits from the 10 s. 324 + 439 1 763 First add the 1 s. 4+9=? Look where the digits go. Next the 10 s. 20 + 30 + 10 = ? Don’t forget that last 10. © hamilton-trust. org. uk 12 Finally add the 100 s. 300 + 400 = ? Year 4

Day 2: Add two 3 -digit numbers using compact written addition. Try 246 + 372 on your boards using the written method. 266 + 372 8 First add the 1 s. 6+2=? © hamilton-trust. org. uk 266 + 372 Let’s check the steps. Set it out clearly. 266 + 372 1 638 266 + 372 1 38 Next the 10 s. 60 + 70 = ? Why is there a 1 under the 300? 13 Finally add the 100 s. 200 + 300 + 100 = ? Year 4

Challenge © hamilton-trust. org. uk 14 Year 4

Addition and Subtraction Partitioning and column addition Objectives Day 3 Add three 3 -digit numbers using compact written addition. © hamilton-trust. org. uk 15 Year 4

Day 3: Add three 3 -digit numbers using compact written addition. 592 + 235 Try 592 + 235 on your whiteboards using the written method. 592 + 235 7 592 + 235 1 27 Set the numbers out with 100 s, 10 s and 1 s lined up. Don’t forget the space above the line for any 10 s digits from adding 1 s or 100 s digits from the 10 s. 592 + 235 1 827 First add the 1 s. Place the answer carefully. Next the 10 s. 90 + 30 = ? Don’t forget the 1 under the 100 s. © hamilton-trust. org. uk 16 Finally add the 100 s. 500 + 200 + 100. Year 4

Day 3: Add three 3 -digit numbers using compact written addition. 123 474 + 332 Let’s try the same method to add 3 numbers! 123 474 + 332 9 Add the 1 s. 3+4+2=? © hamilton-trust. org. uk Let’s check the steps. 123 474 + 332 1 929 123 474 + 332 1 29 Next the 10 s. 20 + 70 + 30 = ? 17 Don’t forget the extra 100! Lastly, the 100 s. 100 + 400 + 300 + 100 = ? Year 4

Day 3: Add three 3 -digit numbers using compact written addition. 238 111 + 216 Now try 238 + 111 + 216 on your whiteboards. 238 111 + 216 1 5 Add the 1 s. 8 + 1 + 6 = 15 Where did you put the digits? © hamilton-trust. org. uk 238 111 + 216 1 65 Next the 10 s. 30 + 10 = ? 18 Set it out neatly! 238 111 + 216 1 565 Lastly, the 100 s. 200 + 100 + 200 = ? Year 4

Challenge © hamilton-trust. org. uk 19 Year 4

Addition and Subtraction Partitioning and column addition Well Done! You’ve completed this unit. Objectives Day 1 Add pairs of 2 -digit numbers mentally. Add 2 -digit numbers to 3 -digit numbers using mental strategies. Day 2 Add two 3 -digit numbers using compact written addition. Day 3 Add three 3 -digit numbers using compact written addition. © hamilton-trust. org. uk 20 Year 4

Addition and Subtraction Unit 1 Problem solving and reasoning questions Complete these additions mentally, with only the answer written down! 78 + 127 = and 348 + 39 = Use a different method for each and explain both of your strategies. Write the missing numbers in this calculation: If 378 is subtracted from a number to leave 284, what was the number? Add 375 + 528 + 194 using expanded column addition. © hamilton-trust. org. uk 21 Year 4

Problem solving and reasoning answers Complete these additions mentally, with only the answer written down! 78 + 127 = 205 348 + 39 = 387 78 + 127 Start with the larger number, 127, and solve by partitioning 78, adding 70 then 8. 348 + 39 Add 40 then subtract 1 to adjust. Other strategies are possible, look for coherence in the explanation. Write the missing numbers in this calculation: If 378 is subtracted from a number to leave 284, what was the number? 662. Some children may be confused by the wording and attempt a subtraction. Add 375 + 528 + 194 using expanded column addition. 1097 Answers such as 987 or 997 suggest children have either forgotten the extra 10 or 100. © hamilton-trust. org. uk 22 Year 4