Make efficient use of subtraction strategies including column subtraction
I can make efficient use of subtraction strategies including column subtraction.
- Year 3
Make efficient use of subtraction strategies including column subtraction
I can make efficient use of subtraction strategies including column subtraction.
Lesson details
Key learning points
- A mental strategy may be more efficient than a column method
- Look carefully at the numbers in a calculation to decide a method
- Column subtraction might be the most efficient method to use if regrouping is needed
Keywords
Efficient - Being efficient means finding a way to solve a problem quickly whilst also maintaining accuracy.
Mental strategy - A mental strategy is a method chosen to find something out which can be done in your head or with some jottings.
Regrouping - The process of unitising and exchanging between place values is known as regrouping.
Common misconception
Pupils may think that column subtraction is always the most efficient strategy where regrouping is needed.
Emphasise calculations where adjustment is the most efficient strategy (e.g. 456 - 199). Regrouping is needed in both the tens and hundreds, but is is not the most efficient strategy.
Licence
Lesson video
Loading...
Prior knowledge starter quiz
6 Questions
Q1.Where is regrouping needed in the column subtraction?
Q2.Where is regrouping needed in the column subtraction?
Q3.Finish the column subtraction. What is the difference?
Q4.How would you subtract 99 from 387?
Q5.Calculate 387 − 99 =
Q6.Complete the column subtraction. What is the difference?
Assessment exit quiz
6 Questions
Q1.Which calculations would it be most efficient to answer using a mental strategy?
Q2.Which calculations would it be most efficient to answer using column subtraction?
Q3.Sam calculates 401− 396 by counting on from 396 He found a difference of .
