Addition and subtraction - Add three-digit and one-digit numbers crossing 10 - Presentation

The lesson on addition and subtraction focuses on a crucial mathematical skill: adding three-digit and one-digit numbers, particularly when this process involves crossing the ten's boundary. The concept of exchanging is central to this lesson, where pupils are reminded of what occurs when more than nine units are present in a place value column. Through a series of activities, students are encouraged to engage with the process of exchanging ones for tens. For instance, when adding 337 and 6, students learn to exchange 10 ones for 1 ten, which is then added to the tens column, resulting in an answer of 343. This method is practiced with various calculations, reinforcing the understanding of how adding to the ones place can impact the tens place.

The lesson includes a range of activities that require students to solve calculations by making exchanges. They use equipment to support their understanding, tackling problems such as adding 248 and 8, or 524 and 7. The process is visually represented, showing how ones are exchanged for tens before being added to the tens column. Additionally, the lesson introduces a method of partitioning numbers into hundreds, tens, and ones to facilitate easier addition. For example, when adding 523 and 8, students learn to partition 23 into 30 and then add 8 to get 31, which is then added to 500 to reach the final answer of 531. The lesson also includes reasoning activities, where students explore patterns in addition and determine which calculations are more complex based on the need for exchanging. Independent work tasks further challenge students to apply their reasoning and explain their strategies.