Starter quiz
- Which of these subtraction expressions can be more efficiently solved by finding the difference?
- 75 − 68 = ✓
- 96 − 19 =
- 32 − 25= ✓
- 83 − 38 =
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What is the missing part in this bar model?- '80' ✓
- Match the numbers so that they make a pair with a sum of 100.
- 20⇔80 ✓
- 40⇔60 ✓
- 75⇔25 ✓
- 95⇔5 ✓
- Use a find the difference strategy to calculate: 54 − 47 = ______
- '7' ✓
- Use a partitioning strategy to find the sum of 135 and 270
- '405' ✓
- Select all the multiples of 10
- 75
- 90 ✓
- 100 ✓
- 103
- 150 ✓
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Exit quiz
Which of these is the correct equation represented by this bar model?- 240 − 270 = ?
- 270 − 240 = ? ✓
- 270 + 240 = ?
- 240 + 270 = ?
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Which of these is the correct equation represented by this number line?- ? = 850 − 810 ✓
- ? = 850 + 810
- ? = 810 + 850
- ? = 810 − 850
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What is the difference between the two values shown in the bar model?- '40' ✓
What is the difference between the two values shown?- '80' ✓
What is the difference between the two values shown?- '90' ✓
- Which of the pairs of numbers have the greatest difference?
- 270 and 290
- 230 and 310 ✓
- 260 and 320
- 250 and 280
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Worksheet
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Presentation
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Lesson Details
Key learning points
- When numbers are close together, the difference between them is small.
- Finding the difference means we count on from the subtrahend to the minuend.
- A number line or a bar model can represent finding the difference.
Common misconception
Children will often reverse the minuend and subtrahend because they don't always appear in the order that they would in an expression.
Give time to ensure that the children understand the bar model representation and encourage them to discuss which number is the minuend and which is the subtrahend before engaging in a strategy for mental subtraction.
Keywords
Minuend - The minuend is the number being subtracted from.
Subtrahend - A subtrahend is a number subtracted from another.
Difference - The difference is the result after subtracting one number from another.
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