Welcome to our lesson on addition! Addition means combining or putting together different quantities. Today we'll solve the problem 3 plus 8 plus 10. Let's start by looking at three separate groups: 3 circles, 8 squares, and 10 triangles. We'll explore different ways to find the total.
Now let's use the visual counting method. We'll count each object individually from 1 to 21. First we have 3 circles, then 8 squares, and finally 10 triangles. By counting them all together, we can see that 3 plus 8 plus 10 equals 21. This method works well but can be time-consuming for larger numbers.
Now let's try a more efficient sequential addition strategy. Instead of counting everything, we add numbers step by step. First, we start with 3, then add 8 to get 11. Finally, we add 10 to 11 to reach 21. This method breaks down complex addition into simpler, manageable steps and is much more efficient than counting individual objects.
Now let's explore the commutative property of addition. This property shows that the order of addition doesn't affect the result. We can group the numbers in different ways: first, 3 plus 8 equals 11, then 11 plus 10 equals 21. Or we can add 8 plus 10 to get 18, then add 3 to get 21. We can also add 3 plus 10 to get 13, then add 8 to get 21. All methods yield the same result of 21.
Now let's learn mental math strategies using friendly numbers. Instead of adding in order, we can look for pairs that make round numbers like 10 or 20. For example, we can add 3 plus 10 first to get 13, then add 8 to get 21. Or we can add 8 plus 10 to get 18, then add 3 to get 21. These strategies make mental calculation much faster and easier than following the original order.