L4 Subtract 3-Digits and 10s Mentally

This Year 3 maths lesson provides a complete, structured approach to teaching pupils how to subtract tens from 3-digit numbers mentally. Designed for the Autumn term Addition and Subtraction unit, the lesson builds on prior work with place value and earlier counting-in-10s learning. The teaching sequence begins with counting back in 10s from different starting points, using a hundred square to highlight the pattern: when subtracting 10, the tens digit changes but the ones digit remains the same unless a hundreds boundary is crossed. Clear modelling demonstrates how place value columns change when tens are subtracted, helping children recognise when the hundreds digit will stay the same and when it will reduce. The practical activity uses number cards and base-10 resources so children can subtract tens from a variety of 3-digit numbers before recording their calculations. Differentiation is built in through the optional use of manipulatives such as place value counters, base 10, or number lines. The plenary encourages reasoning and error analysis as students evaluate incorrect answers from example pupils and explain their thinking. Key questions, conceptual prompts, and reflection opportunities support strong understanding of place value and mental fluency with subtracting tens.