The story was about a baby bird who lost his mother and went looking for her. First he asked a pig if he had seen her, then a cow and finally a buck.  

The two children who chose to draw the cow have seen cows in books, of course, but when the proud artists presented their work to their teachers it was all they could do not to laugh. They wouldn't hurt their little charges' feelings for anything in the world but they were very glad it was playtime and they could enjoy a good laugh with their colleagues out of hearing - in the classroom.  

There wasn't much to be seen of the cow but they sure had taken trouble to draw the udder - which they didn't refer to as an 'udder'. 

A family friend who is a dairy farmer says he thinks the children should be praised for recognising which part of the cow is the most important.