Addition and Subtraction - Checking strategies - Presentation

In a series of educational slides focusing on checking strategies for addition and subtraction, students are introduced to the concept of inverse operations. The lesson encourages students to use subtraction as a method to verify the accuracy of addition calculations. For example, after performing an addition such as 3,200 + 4,560 = 7,760, they can check the result by subtracting one of the addends from the sum, confirming that 7,760 - 3,200 equals the other addend, 4,560, and vice versa. This approach solidifies their understanding that subtraction is the inverse of addition and that this relationship can be used to validate their answers.

Further activities guide students to explore various addition and subtraction facts based on a single calculation, like knowing that if 1,410 + 4,420 equals 5,830, then 5,830 - 1,410 must equal 4,420, and so on. They are also prompted to consider the order of numbers in addition and whether the equal sign must always be at the end of a calculation. The lesson progresses to more complex tasks, such as completing number pyramids and creating rules to simplify addition of multiple numbers by looking for number bonds. These exercises not only enhance computational fluency but also develop reasoning skills as students discover multiple ways to approach and check their work.