Addition and Subtraction - Subtract a three digit number from a three digit number (exchange) - Presentation

The lesson on subtracting a three-digit number from another three-digit number with exchange is a crucial mathematical concept taught to enhance students' understanding of place value and subtraction across tens and hundreds boundaries. This lesson involves recapping the process of subtracting numbers that require borrowing from a higher place value column when there isn't enough in the column to subtract. For instance, students will explore what to do when they encounter a scenario where the digits in the tens or hundreds column are not sufficient to subtract the corresponding digits of the other number.

Using visual aids such as counters to represent hundreds, tens, and ones, students are guided through practical activities to complete subtraction calculations. For example, when subtracting 224 from 118, students learn to exchange a ten for ten ones to facilitate the subtraction, resulting in the correct answer of 106. Further activities include solving column subtraction problems while showing the exchanges made, reinforcing the concept through hands-on learning. The lesson also incorporates reasoning tasks where students identify and correct mistakes in subtraction calculations, work out missing digits, and explain their thinking behind the process of exchanging. These exercises not only solidify their computational skills but also deepen their conceptual understanding of the exchange process in subtraction.