Addition and subtraction within 20 - Add by making 10 2 - Presentation

Lesson 7 of the addition and subtraction series focuses on the strategy of 'Add by Making 10', which is a cornerstone of mental arithmetic for young learners. This technique leverages the understanding of number bonds to 10, an essential skill for efficient calculation. Students are encouraged to recall and discuss these number bonds with a partner, setting the stage for the day's learning objective. The lesson introduces a practical approach where students partition numbers to add up to a base of 10, facilitating easier addition of larger numbers. For instance, to add 6 and 7, one could partition 7 into 4 and 3, then add 6 and 4 to make 10, and finally add the remaining 3 to reach the total of 13. This method is visually supported by the use of ten frames, which are graphical tools that help students clearly see the partitioning and combining of numbers.

Further activities involve applying the 'Add by Making 10' strategy using various tools such as counters and number lines. For example, Leanna demonstrates how she partitions the number 7 to add to 6 on a tens frame, while another student, Malachi, showcases the use of a number line to add 6 and 8 by breaking down the number 8 into two 4s for easier addition. These activities are designed to reinforce the concept through repetition and variation, allowing students to grasp the method from different perspectives. The lesson also includes reasoning tasks where students evaluate different approaches to adding numbers and decide which is most effective, encouraging critical thinking and a deeper understanding of the mathematical concepts at play. Independent work and group discussions round out the lesson, ensuring that students have the opportunity to practice the strategy and articulate their understanding of how partitioning numbers can simplify the addition process.