Most of the time, my answers to the strangeness of English spelling is simply, "its French."
Today I had a discussion about "OF" with a little one who likes to ask a lot of questions. In these situations, I have to resort to something that my oldest child invented: Alphabet letter personalities and conspiracies. It has helped us through phonics for many years. Example:
Child: "Why is UV spelled OF? F doesn't say V!"
Me: "Because F is pretending to be V."
Child: "But WHY???"
Me: "Because U and V decided to go to Hawaii, and O and F are pretending to be them while they are gone."
Child: "OF should be OFF not UV!"
Me: "Well, U and V decided that they did not want to say "OF" anymore, they wanted to be Ultra Violet instead, so they retired to Hawaii, where they are now Ultra Violet. O and F had to fill in and pretend they are U and V now."
Child rolls his eyes and goes on the to the next word.