Addition Within 20
Definitions
Do you know what happens when you get more toys or candies? You are adding! Let’s see: if you have 8 red cubes and someone gives you 6 more blue cubes, how many cubes do you have now?
\(+\) 
\(=\)
\(+\) \(=\)
Now you have 14 cubes! In math, we write it like this: $$8 + 6 = 14$$ \(+\) \(=\) 
\(+\) \(=\)
Definition Addition
Addition means putting things together. When we add, we find how many we have in total.
- The \(+\) symbol means "add."
- The \(=\) symbol shows that the two sides are the same.
- Numbers: $$\textcolor{colordef}{8} + \textcolor{colorprop}{6} = \textcolor{olive}{14}$$
- Cubes: \(+\) \(=\)
- Fingers:
\(+\) 
\(=\) 
- Words: $$\textcolor{colordef}{\text{eight }}\text{plus}\textcolor{colorprop}{\text{ six}}\text{ equals }\textcolor{olive}{\text{fourteen}}$$
- Part whole model:
Number Line Method
Method Adding using Number Line
We want to find \(8+6\).
- Place a marker on 8.
- Move 8 steps forward.
Making 10 Method
Method Adding with the Making 10 Method
To add \(\textcolor{colordef}{7}+\textcolor{colorprop}{4}\), we can make 10 first and then add what’s left!
- Start with \(\textcolor{colordef}{7}\)
- Make 10: Ask yourself, How many more do we need to get to 10? We need \(\textcolor{colorprop}{3}\) more to make 10. Since we are adding \(\textcolor{colorprop}{4}\), let’s split the \(\textcolor{colorprop}{4}\) into \(\textcolor{colorprop}{3}\) and \(\textcolor{colorprop}{1}\).
- Add: First, add \(\textcolor{colordef}{7} + \textcolor{colorprop}{3}\) to make 10. Now add the \(\textcolor{colorprop}{1}\) left over from splitting \(\textcolor{colorprop}{4}\), so \(10 + \textcolor{colorprop}{1} = 11\).
-
- \(\begin{aligned}[t]\textcolor{colordef}{7}+\textcolor{colorprop}{4}&=\textcolor{colordef}{7}+\textcolor{colorprop}{3}+\textcolor{colorprop}{1}\\&=10+\textcolor{colorprop}{1}\\&=11\\\end{aligned}\)