How did Dorothy and the Scarecrow decide on which way to go?

In the Wizard of OZ movie, Dorothy sets off on the yellow brick road to find the Wizard of OZ.

She came to a crossroad, and didn't know which way to go.

She meets the Scarecrow, and he had no idea which way to go either.

They randomly decided to turn left while they were dancing.

It seemed to me that they had no reason to go that way.

Why did they go that way?