When we introduce shapes to our little ones, we always start basic and easy. They might need a little more time to get acquainted with shapes, that's why it's a good thing to point them at the same time to objects they already are familiar with, e.g. this toy car's wheel is round like a circle, the TV is like a rectangle, our toasted bread is square.
Print out the free flashcards! They will become your tool of choice in teaching not only the basic shapes, but colors too!