Seven is a Funny Word

As rambunctious as Luke is, he somehow takes time to think about words (which I totally eat up being an English teacher and all.) He told me in the car the other day that "seven is a funny word." When asked why, he said that the number seven just doesn't look like a seven sounds. Interesting observation. His other questions about words.... *Where is the "pop" in popcicle? Is it when I pop it in my mouth? Also, why isn't there a "tree" growing in our pantry? Never thought of that one. He did understand, however, why there is "water" in watermelon.