Subtract 3-Digits from 3-Digits 1 Year 3 Addition and Subtraction Learning Video Clip
Step 15: Subtract 3-Digits from 3-Digits 1 Year 3 Addition and Subtraction Learning Video Clip
Ali is transporting animals between conservation parks. She needs help to ensure the animals are transported safely.
More resources for Autumn Block 2 Step 15.
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Discussion points for teachers
1. Explain to Ali how she could solve the calculation.
Discuss calculating mentally. How could we mentally calculate the answer? Do we have to subtract? Why could we count on to solve this problem?
She can work mentally, counting on from 204 to 509 which = 305kg.
2. How much further must she drive?
Discuss what the number line shows us already. How can we use the number line to help us? What does each jump show us?
453 – 121 = 332 miles
3. What mistakes has she made?
Discuss working systematically through the calculation to find all the mistakes. What is wrong with the answer? Discuss commutativity and how we cannot swap the numbers over in a subtraction calculation.
She has not lined up the numbers properly and has used commutativity which does not work in a subtraction calculation.
485 – 271 = 214.
4. Which truck could Leo fit in?
Discuss what each bar model represents. Which calculation will allow us to calculate the missing number? How will we know which truck Leo can fit in?
Truck B: 659 – 433 = 226
5. What could the calculation be?
What does each part of the calculation represent? Discuss which digits can and cannot fit in each space and why. Work systematically to find all possibilities.
Various answers, for example: 985 – 614 = 371, 995 – 624 = 371, 885 – 613 = 272, 795 – 622 = 173
Optional discussion points:
Discuss reasons for transporting animals. Discuss how it is done humanely and safely.
National Curriculum Objectives
Mathematics Year 3: (3C1) Add and subtract numbers mentally, including three-digit number and ones, three-digit number and tens, three-digit number and hundreds
Mathematics Year 3: (3C2) Add and subtract numbers with up to three Digits, using formal written methods of columnar addition and subtraction
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