Teach Addition Using Number Lines And Partitioning

Hi, I'm Rebecca, and today we're going to look at informal methods for addition. So let's have a look at an addition problem. Manelle has 23 stickers. Her dad gives her 15 more. How many stickers does she have altogether? So we can show this problem pictorially on a bar model. We know what our two parts are. We have 23 and 15. What we don't know is what the total amount is. So we can show that by putting a question mark here. The first informal method that we can use is partitioning. Can partition 23 into 20 and 3, and we can partition 15 into 10 and 5. Now we can add the ones 5 add 3 gives us 8 and 20 add 10 gives us 30, giving us an answer of 38. Our second informal method we can use is counting on. On a number line. So we can start with our biggest number here, which is 23. And we're going to do one jump of 10 to take us to 33. You'll notice that my jump is bigger because I'm representing 10. And then we can do five small jumps of one to take us to 38. So there you go. That's informal methods for addition.