Measurement Length and Perimeter - Subtract Lengths - Planning

In a Year 4 mathematics lesson focused on measurement and perimeter, students are tasked with learning how to subtract lengths. The lesson aims to develop their ability to find the difference between two lengths and enhance their mental subtraction strategies. Key vocabulary such as 'length', 'height', 'metres', 'centimetres', 'difference', and 'subtract' is introduced. Students begin by completing a set of 'fluent in four' questions to recap their previous learning. The class then moves on to practical activities where they measure objects with rulers and express the differences in lengths as subtraction sentences. The importance of using the same units for easier subtraction is emphasised.

During the lesson, students explore different methods for subtracting lengths, including counting on and using visual models such as bar models and part-whole models. They engage in partner work, challenging each other with problems that require the use of these models to solve. The lesson includes reasoning tasks where children read word problems, extract key information, and represent the problems visually to find the solution. Independent learning is supported by differentiated worksheets that cater to varying levels of ability, from working towards expected standards to achieving greater depth. Students are encouraged to reflect on what they've learned, the skills they've used, and any challenges they faced. Common misconceptions such as inaccuracy in mental calculations and confusion when converting between units are addressed to ensure a solid understanding of subtracting lengths.