Found at several places on the Internet:

FLOWERS ARE RED
Harry Chapin

The little boy went first day of school. He got some crayons and started to draw.
He put colors all over the paper, for colors was what he saw.
And the teacher said, "Whatcha doin', young man?" "I'm paintin' flowers," he said.
She said, "It's not the time for art, young man, and anyway flowers are green and red.
There's a time for everything, young man, and a way it should be done.
You've got to show concern for everyone else, for you're not the only one."

And she said, "Flowers are red, young man. Green leaves are green.
There's no need to see flowers any other way than the way they always have been seen."

But the little boy said, "There are so many colors in the rainbow, so many colors in the morning sun,
So many colors in the flower and I see every one."

Well the teacher said, "You're sassy. There's ways that things should be.
And you'll paint flowers the way they are, so repeat after me."

And she said, "Flowers are red, young man. Green leaves are green.
There's no need to see flowers any other way than the way they always have been seen.

But the little boy said, "There are so many colors in the rainbow, so many colors in the morning sun.
So many colors in the flower and I see every one."

The teacher put him in a corner. She said, "It's for your own good.
And you won't come out 'til you get it right, and are responding like you should."
Well, finally he got lonely. Frightened thoughts filled his head.
And he went up to the teacher, and this is what he said:
And he said, "Flowers are red. Green leaves are green.
There's no need to see flowers any other way than the way they always have been seen."

Time went by like it always does, and they moved to another town.
And the little boy went to another school, and this is what he found.
The teacher there was smilin'. She said, "Painting should be fun.
And there are so many colors in a flower, so let's use every one."

But that little boy painted flowers in neat rows of green and red.
And when the teacher asked him why, this is what he said:
And he said, "Flowers are red. Green leaves are green.
There's no need to see flowers any other way than the way they always have been seen."