What is the most difficult contraction to spell?

That's a tricky question! There isn't really one "most difficult" contraction to spell, as it depends on the individual and their spelling strengths and weaknesses. However, some contractions can be particularly challenging due to:

* Homophones: Words that sound the same but are spelled differently, like "its" and "it's."

* Unusual letter combinations: Contractions often use apostrophes, which can be tricky to place correctly.

* Common misspellings: Some contractions, like "don't" and "can't," are often misspelled.

Here are some contractions that people often find difficult to spell:

* It's vs. its: Remember "it's" means "it is" or "it has," while "its" is the possessive form of "it."

* They're vs. their vs. there: "They're" is a contraction of "they are," "their" is possessive, and "there" indicates a place.

* You're vs. your: "You're" is a contraction of "you are," while "your" is possessive.

* Who's vs. whose: "Who's" is a contraction of "who is" or "who has," while "whose" is possessive.

* I'm vs. I am: While both are correct, "I'm" is more common in informal writing.

Ultimately, the best way to avoid spelling errors with contractions is to practice and be mindful of the different forms!