Why English Can Be Difficult To Teach

You know how they say english is just difficult to teach. Some things you just know or you don't. And what I was teaching was just the alphabet....

Here's what happened when I was teaching Kaitlyn the letters of the alphabet:

Letter "I"
"Mummy, look at the turtle!"

Letter "F"
Me: (makes the sound of the letter F) That's the sound of letter "F". Can you say it?
Kaitlyn: No...."ribbit, ribbit"

I can't say she's wrong right?