L8 Find 100 Less

This Year 3 maths lesson teaches children how to find 100 less than a number within 1,000, building on previous place value learning from Year 2 and earlier Year 3 lessons. The starter revisits counting in multiples of 100, this time counting backwards from 1,000 to 0, helping children observe that the hundreds digit decreases while the tens and ones digits remain the same. Teachers can briefly introduce the idea of negative numbers, though this is not explored in Year 3. In the introduction, students explore finding 100 less using place value charts and Base 10 counters. Examples such as 985 decreasing by 100 to 185 demonstrate how hundreds are removed and the importance of placeholders when numbers include zeros (e.g., 106 becomes 6 when 100 is subtracted). Students learn that the tens and ones digits often remain unchanged even when hundreds are removed. During the activity, children generate 3-digit numbers, represent them on place value charts with Base 10 counters, and find 100 less by removing a 100-counter from the hundreds column. They are encouraged to explore numbers with 0 tens or 0 ones to see how this affects their subtraction and reinforce understanding of placeholders. The plenary consolidates learning with problem-solving and riddles, encouraging students to reason backwards, e.g., identifying a number where 610 is 100 less than the original. Key questions guide understanding: What happens to the hundreds digit when subtracting 100? Which digits change or stay the same? How do placeholders work? This resource is ideal for teachers seeking a structured, hands-on Year 3 lesson on finding 100 less, place value, and subtraction within 1,000, with activities designed to strengthen conceptual understanding and address common misconceptions.