Main content

## Early math review

### Unit 2: Lesson 1

What is addition? What is subtraction?# Intro to addition

Learn what it means to add. The examples used are 1+1 and 2+3. Created by Sal Khan.

## Video transcript

Voiceover:Let's think about what it means to add numbers. So let's start with 1. 1 plus. 1 plus 1. What is this going to be equal to? One way to think about this is we have 1 thing, and that thing
will be a purple circle. So let me put that here. So that's this 1 thing. I'm just going to represent it with a purple circle. And I'm going to add another 1 thing. And since this is in blue, I'll make that other circle, I'll
make that in blue as well. So let me put that right over here. So 1 plus 1. 1 plus 1. How many total circles do I now have? Well, I now have 2 circles. I now have 2 circles. 1 plus 1 is equal to, is equal to 2. Okay, you're saying all
right Sal, all right, that makes sense. Let's do this with larger numbers. So let's say we want
to know what equals ... And I'll put a question mark over here. So, question mark. What equals ... So something is equal to, is equal to, let's say, 2, 2, 2 plus 3. Something is equal to 2 plus 3. What is this something going to be? I encourage you to pause
the video and think about it on your own. Well, you could view
this as, I have 2 objects and then we're going to
add another 3 objects. How many total objects would I have? So you have your 2 objects, which I'll use purple circles again. So let me ... Let me, so, we have 1
and 2 purple circles. This is the 2 right over here. And then to that we're
going to add 3 more. 3 more circles. I'll represent those in blue because we wrote the 3, here, in blue. So that is 1, 2, and 3. So how many total circles do we now have? Well, we could count them. We have 1, 2, 3, 4, 5. In fact, let me count that. 1, 2, 3, 4, 5 circles. So 2 plus 3. 2 things plus another
3 things are 5 things. So our question mark, right over here, is equal to 5. So instead of writing the question mark right over here, let me clear that out. I could say 5 is equal to. I could write down that
5 is equal to 2 plus 3.