The mother, more than a little surprised, tried to keep her cool.
“That’s interesting,” she said. “How do you make babies?”
“It’s simple,” replied the girl. “You just change ‘y’ to ‘i’ and add ‘es’.”
The girl was talking about spelling rules—how to make words plural
(like “baby” to “babies”) by changing “y” to “i” and adding “es.”