Starter quiz
- In the following equation, which number is the subtrahend? 21 − 4 =17
- 21
- 4 ✓
- 7
-
- Solve the following calculation mentally by adjusting the minuend and subtrahend. 76 − 22 = ______
- '54' ✓
- Solve the following calculation using a mental strategy. ______ = 150 − 68
- '82' ✓
- Solve the following calculation mentally by adjusting the subtrahend and then the difference. 165 − 27 = ______
- '138' ✓
- Solve the following calculation using a mental strategy. ______ = 4,050 − 98
- '3,952' ✓
- Select the equivalent expressions (equal value) from the list below.
- 105 − 56 ✓
- 254 − 205 ✓
- 300 − 156
- 85 − 34
-
Exit quiz
- Use a known fact to find the missing number in this subtraction equation. 46 − 0.35 = ______
- '45.65' ✓
- Use a mental strategy. ______ = 223 − 0.57
- '222.43' ✓
- Use a mental strategy. 27.43 − 0.22 = ______
- '27.21' ✓
- Use a mental strategy. ______ = 274.86 − 0.54
- '274.32' ✓
- Use a mental strategy. 1,367,000 − 17,000 = ______
- '1,350,000' ✓
- Use a mental strategy. 9,284,000 − 22,000 = ______
- '9,262,000' ✓
Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Compensation can be used to simplify subtraction calculations.
- Equivalence can be used to simplify subtraction calculations.
- A number line can be used to represent compensation and equivalence.
Common misconception
Known facts in this lesson include complements and two-digit subtractions which some children may find challenging to recall fluently.
It's a good idea, if possible, to do some pre-teaching here to develop the confidence of the children who might find the known facts aspect provides extra cognitive load. Supplying scaffolds such as key bonds to 20 and 100 may also benefit.
Keywords
Minuend - The minuend is the number being subtracted from.
Subtrahend - A subtrahend is a number subtracted from another.
Partition - Partition is the act of splitting an object or value down into smaller parts.
Adjust - When you adjust you make a change to a number. This is done to make a calculation easier to solve mentally.
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