L6 Subtract 3-Digits and 100s Mentally

This Year 3 maths lesson provides a structured and engaging approach to teaching children how to subtract hundreds from 3-digit numbers mentally. It forms part of the Autumn term Addition and Subtraction sequence and builds on essential place value understanding from earlier lessons. The session begins with counting back in 100s from different starting numbers, helping pupils recognise the pattern that only the hundreds digit changes while the tens and ones remain the same when subtracting 100. The introduction uses clear modelling to show how subtracting hundreds affects each place value column, reinforcing that the tens and ones digits stay constant unless crossing a boundary. Children then practise counting backwards in 100s aloud, supporting fluency and confidence in mental strategies. The practical activity includes a cut-up matching resource where pupils pair subtraction calculations with their correct answers before recording them in their books. Manipulatives such as place value counters, base 10, or number lines can be used for additional support and differentiation. The plenary encourages reasoning and problem solving, with a partner task structured around a subtraction word problem. Key questions guide mathematical thinking and help teachers assess understanding while addressing common place value misconceptions. This complete lesson strengthens fluency, reasoning and confidence when subtracting hundreds mentally.