Addition and Subtraction - Subtract four digit numbers (one exchange) - Presentation

Building upon students' existing understanding of subtraction, this lesson focuses on subtracting two four-digit numbers that require one exchange. The concept of exchange is crucial when a digit in the number being subtracted from is smaller than the corresponding digit in the number being subtracted. For example, students are asked to subtract 2,126 from 5,533 and must recognize that they cannot subtract 6 from 3 without exchanging. They learn that by exchanging a 10 for 10 ones, they can perform the subtraction, resulting in an answer of 3,407. The lesson includes a series of activities that progressively teach pupils how to handle exchanges in different places of the number, reinforcing their fluency and reasoning skills in subtraction.

As the lesson advances, students encounter increasingly complex scenarios, such as subtracting 1,572 from 3,655, where they need to exchange a 100 for 10 tens to proceed with the subtraction. The lesson plan also integrates practical problems, such as determining the number of parents accompanying children and teachers on a trip to the National Museum. This real-life application requires students to combine addition and subtraction to find the answer. Moreover, the lesson encourages the exploration of patterns and the range of possible answers in subtraction problems, as well as the use of place value counters and column subtraction methods to understand and explain the exchange process. The lesson's structured approach aims to solidify the students' grasp of exchanging in subtraction through a variety of engaging activities and discussions.