Addition and subtraction - Subtract a two-digit number from a ​three-digit number crossing 100 - Planning​

In a Year 3 mathematics lesson centred around subtraction, the objective is for students to confidently subtract a two-digit number from a three-digit number, particularly when this action crosses the 100 boundary. The lesson equips students with the necessary vocabulary such as 'subtraction', 'hundreds', 'tens', 'ones', 'exchange', and 'multiple', among others. The class begins with a recap of prior learning and then moves on to practical activities to reinforce the concept. One such activity involves using chalk to draw number lines on the playground, where students physically jump back in tens to understand the subtraction process. This kinesthetic approach helps children to visualise and remember the sequence of numbers, especially when crossing from one hundred to the next.

The lesson then progresses to more abstract methods, such as using part-whole models to partition numbers and facilitate subtraction. Students are encouraged to revisit their understanding of number bonds to 100, which is crucial for this step. The session also introduces the concept of adjusting numbers to make subtraction more efficient, prompting students to create and solve problems with their peers. Throughout the lesson, key questions are posed to deepen understanding, such as how to exchange tens for hundreds and how to partition numbers to subtract more efficiently. The lesson concludes with a reflection on the skills learned and a commitment to remember the strategies used. Differentiated activities cater for varying levels of ability, from working towards expected standards to achieving greater depth in the subject.