Equivalent fractions are equal and cover the
same area of wholes that are the same size.
First, model
$\frac{1}{3}$ using a grid.
Add a vertical line down the middle of the model so that it is divided into six equal parts, but the same area of the whole is shaded.
The second model is divided into six equal parts, and two parts are shaded. So, the second model shows $\frac{2}{6}$.
Since the model of $\frac{2}{6}$ has the same area of the whole shaded as the model of $\frac{1}{3}$, $\frac{2}{6}$ is equivalent to $\frac{1}{3}$.
Next, add two more vertical lines to the model so that it is divided into twelve equal parts, but the same area of the whole is shaded.
 
 

$\frac{1}{3}$   $\frac{2}{6}$   
The third model is divided into twelve equal parts, and four parts are shaded. So, the third model shows $\frac{4}{12}$.
Since the model of $\frac{4}{12}$ has the same area of the whole shaded as the models of $\frac{1}{3}$ and $\frac{2}{6}$, $\frac{4}{12}$ is equivalent to $\frac{2}{6}$ and $\frac{1}{3}$.