The Year 2 Subtract Two 2-Digit Numbers Across a 10) 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
subtract: Take one quantity away from another.
ones: Individual units that make up a whole number.
tens: A group of 10 ones together is the same as 1 ten.
exchanging: Exchanging can occur when completing calculations.
Varied Fluency
Knowledge Organiser
• Designed to support all children via key information and examples.
Scaffolded Examples
• Counting tens and ones in Base 10; exchanging 1 ten for 10 ones; checking the ones to see if an exchange is needed.
Support
• Q1: Subtract with an exchange already made; the start of the working is given.
• Q2: Find which subtraction needs an exchange; the ones to compare are given.
• Q3: Find the difference on a bar model; the greater number is given and the working is started.
Core
• Q1: Subtract using Base 10 with the exchange already made.
• Q2: Work out two subtractions and decide which needs an exchange.
• Q3: Find the difference on a bar model; the smaller number is written first.
Stretch
• Q1: Make the exchange yourself, then subtract using Base 10.
• Q2: Decide which needs an exchange, including numbers with 0 ones.
• Q3: Complete a blank bar model and write the subtraction to find the difference.
Reasoning and Problem Solving
Support
• Q1: Reasoning – decide whether a character needs to exchange 1 ten, using Base 10 in a place value chart.
• Q2: Reasoning – decide which of two children has subtracted correctly after the exchange has been shown.
• Q3: Problem Solving – find subtractions from a given number that need an exchange, with the tens digit given.
Core
• Q1: Reasoning – decide whether a character has subtracted correctly after exchanging 1 ten.
• Q2: Reasoning – decide which of two children has found the difference correctly using a bar model.
• Q3: Problem Solving – find pairs of 2-digit numbers with a given difference that need an exchange.
Stretch
• Q1: Reasoning – test a general statement about exchanging, or check a missing digit.
• Q2: Reasoning – decide which of two children is correct about a missing digit or a missing part.
• Q3: Problem Solving – use four digit cards to make subtractions that need an exchange.
Deeper Reasoning
The question in this set focuses on problem solving subtraction calculations that cross a 10 on loop cards to deepen understanding of addition and subtraction of 2-digit numbers using concrete objects and pictorial representations.
