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Addition and Subtraction
Objectives
To identify number facts and strategies for solving subtractions questions.
Resources
Abacus Workbook 1 | 📄 Using number facts and place value for subtraction | Coloured pens
Vocabulary
subtraction | number facts | strategies
Today's Lesson
What to Get Ready
Write these subtractions out: 26 – 6, 30 – 7, 13 – 4, 20 – 8, 9 – 2, 14 – 4, and 23 – 7.
Introduction
Explain that just as some of the additions we looked at in the last lesson could be worked out using learned facts to help, the same is true of subtractions.
Show your student the subtractions you have written and ask, ‘Can you see any we could work out using learned facts?’
Your student should circle with a coloured pen the number facts that they know without having to work them out.
Say: ‘Note that we can find the answers to some of the subtractions using place value, taking off multiples of 1 from 2-digit numbers, such as 26 – 6. Can you see any others?’
Ask them to circle with a different coloured pen the subtractions they would choose to do using place value.
Now sort the calculations into two groups: those best solved by counting back; those best solved using place value/number facts.
This video talks through how to sort these subtractions depending on these strategies used.
Main Activity
Give your student the 📄 Using number facts and place value for subtraction to sort into groups according to how they might best be solved: using place value or number facts or counting back.
Then they need to solve the questions.
Ask: ‘Are you using the quickest strategy? How do you know?’
Workbook
To help your student consolidate their learning from today, please ask them to complete the activities on page 17 of Abacus Workbook 1.