Shared Sides

Can you follow this coloring rule?

Now, it's time to start coloring shapes.

There is only one rule:

Two shapes that share a side cannot be the same color.

Let's start by reviewing the sides of shapes. A square has 4 sides. Trace them with your finger.

Great! Now, let's put 4 squares together. Trace all of the sides on each square with your finger.

Did you notice that some of the squares shared sides? That is the key to following the new coloring rule. How can we color them so that squares that share sides are different colors?

Trace your finger around all of the sides of the red squares. Then, trace your finger around all of the sides of the yellow squares. Yes, we did it! No squares with shared sides are the same color.

Question

How many colors did you use?