The Year 4 Efficient Subtraction PowerPoint guides both teachers and children through the lesson, including use of the varied fluency, reasoning and problem solving, deeper reasoning and scaffolded resources. Key learning information about this step:
Key Vocabulary
efficient: To choose the best method to solve a calculation. Sometimes a mental method can be quicker than a written one if there are no exchanges.
finding the difference: Involves finding how far apart two given numbers are.
constant difference: When the same amount is added to or subtracted from both numbers in a subtraction, the difference stays the same. For example: 64 – 29 = 65 – 30.
informal written methods: Support mental calculations; can include notes, diagrams or representations.
Varied Fluency
Knowledge Organiser
• Designed to support all children via key information and examples.
Scaffolded Examples
• Subtracting 1 from both 3-digit numbers and adding 2 to both 4-digit numbers using sentence stems; checking which subtraction has the same answer.
Support
• Q1: Subtract 1 from both 4-digit numbers; the new first number is given.
• Q2: Add a given amount to both 4-digit numbers; a number line shows it.
• Q3: Find 4-digit subtractions with the same answer; a hint is given.
Core
• Q1: Subtract the same amount from two 4-digit numbers; choose it yourself.
• Q2: Add the same amount to reach a multiple of 1,000; 4-digit numbers.
• Q3: Find 4-digit subtractions with the same answer, then calculate it.
Stretch
• Q1: Subtract 10 or more from both numbers; one has a 3-digit number.
• Q2: Add a 2-digit amount to reach a multiple of 1,000; one is 3-digit.
• Q3: Find subtractions with the same answer; numbers change by up to 15.
Reasoning and Problem Solving
Support
• Q1: Reasoning - explain whether a character has subtracted 1 from both 4-digit numbers.
• Q2: Reasoning - decide whether subtractions are matched to ones with the same answer; a tip is given.
• Q3: Problem Solving - find subtractions from 6,000 or of 1,998 in a range; the change is given.
Core
• Q1: Reasoning - explain whether a character has changed both numbers by the same amount.
• Q2: Reasoning - decide whether 4-digit subtractions are matched to ones with the same answer.
• Q3: Problem Solving - find subtractions with an answer in a range, then change both numbers.
Stretch
• Q1: Reasoning - explain whether a character has changed both numbers correctly, including in opposite directions.
• Q2: Reasoning - decide whether matches with changes of 10 or more and 3-digit numbers are correct.
• Q3: Problem Solving - find subtractions that meet two conditions, then change both numbers.
Deeper Reasoning
The questions in this set focus on problem solving with efficient subtraction methods to deepen understanding in subtracting 4-digit numbers using efficient methods and solving addition and subtraction two-step problems in contexts, deciding which operations and methods to use and why.
