Addition and subtraction - Check answers - Presentation

In the culminating lesson on addition and subtraction, students are introduced to the concept of using inverse operations to verify their answers. The term 'inverse' is explored, prompting a class discussion on its meaning in the context of mathematics. The lesson's objective is for students to become adept at checking the accuracy of their addition by employing subtraction, and vice versa. To achieve this, they engage in a series of activities where they are presented with addition number sentences and tasked with crafting corresponding subtraction sentences to confirm the results. For example, if given the sum 26 + 51 = 77, students would check it by calculating 77 - 26 to see if it equals 51.

Moving forward, the lesson involves an activity where the process is reversed; students use addition to check the results of subtraction sentences. Given a subtraction such as 56 - 14 = 42, they are encouraged to add the difference and the subtrahend, in this case, 42 + 14, to verify that the sum equals the minuend, 56. The lesson also incorporates reasoning exercises where students are asked to consider the validity of statements regarding checking answers and to solve problems that require checking using inverse operations. Additionally, independent work activities challenge students to apply these verification skills to various calculations and word problems, reinforcing their understanding of the relationship between addition and subtraction and the importance of checking their work for accuracy.