Choose the most efficient strategy to subtract from a 3-digit number
I can choose the most efficient strategy to subtract from a 3-digit number.
- Year 3
Choose the most efficient strategy to subtract from a 3-digit number
I can choose the most efficient strategy to subtract from a 3-digit number.
Lesson details
Key learning points
- By looking carefully at the minuend and subtrahend, we can choose the most efficient subtraction strategy.
- When numbers are close together, finding the difference is the most efficient strategy.
- Sometimes, we can use known addition facts to make finding the difference even more efficient.
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.
Partition - Partition is the act of splitting an object or value down into smaller parts.
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.
Ensure that the children spend time understanding the context, either through discussion of the problem or through visual representations such as bar models. It's also worth spending time on vocabulary by playing fun word games or charades.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What is the missing whole in this bar model?
Q2.Complete the missing word minuend − subtrahend = __________
Q3.Use a find the difference strategy to calculate: 72 − 65 =
Q4.What is the difference between the two values shown?
Q5.Use a partitioning strategy to calculate 690 − 270 =
Q6.Which of the pairs of numbers have the smallest difference?
Assessment exit quiz
6 Questions
Q1.What is the equation being shown here?
Q2.Which strategy is being shown in this number line? Partitioning or counting on / back to find difference
Q3.Use an efficient strategy to calculate the missing part in the bar model.
