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# Week 5 - 6 Addition and subtraction

National curriculum content

• Add and subtract numbers with up to 4 digits using the formal written methods of columnar addition and subtraction where appropriate
• Estimate and use inverse operations to check answers to a calculation
• Solve addition and subtraction two-step problems in context, deciding which operations and methods to use and why

Lesson objectives

1. Add and subtract 1s, 10s, 100s and 1,000s
2. Add two 3-digit numbers – not crossing 10 or 100
3. Add two 4-digit numbers – no exchange
4. Add two 3-digit numbers – not crossing 10 or 100
5. Add two 4-digit numbers – one exchange
6. Add two 4-digit numbers – more than one exchange
7. Subtract a 3-digit number from a 3-digit number - no exchange
8. Subtract two 4-digit numbers - no exchange
9. Subtract a 3-digit number from a 3-digit number - exchange
10. Subtract two 4-digit numbers - one exchange
11. Subtract two 4-digit numbers – more than one exchange
12. Efficient subtraction
14. Checking strategies

What we want children to know

• Recognise patterns when we add and subtract 1, 10, 100s and 1,000s
• How to use their place value knowledge to confidently exchange in addition and subtraction calculations
• Confidently understand that we can only hold single digits in each column, anything over must be exchanged
• Learn to write formal written methods of column addition
• Be able to partition two-digit numbers in order to add and subtract from them
• Be able to confidently estimate an answer by using inverse methods to check answers
• How to independently select which operation methods to use when answering two-step problems

What skills we want children to develop

Use knowledge to solve Reasoning and Problem Solving questions such as:

Prove it

Rosie adds 2 numbers together that total 4,444. What could the numbers be? How many ways can you find?

Jack says: “When I add two numbers together I will only ever make up to one exchange in each column.” Do you agree?

Mathematical Talk

• If we are adding tens, are the digits in the tens column the only ones that change?
• Can you represent ___ using the equipment?
• How many ones are there altogether? Can we make an exchange? Why?
• Why is it important to show the exchanged digit in the column method?
• Why is it important to line up the digits in the correct column when adding?