In the first three chapters of To Kill a Mockingbird, what was Calpurnia's fault?

According to Scout, who is the narrator of the story, Calpurnia has many faults. It is only later in the story that Scout comes to appreciate Calpurnia, who is the family's cook. In the first chapter of the book, Scout introduces Calpurnia. She describes the woman as being nearsighted and having to squint all the time because of it. Scout describes Calpurnia's hands as being "wide as a bed slat and twice as hard." This shows that Calpurnia is a disciplinarian around the Finch house, which naturally a child would dislike and consider to be a fault. Scout considers Calpurnia to be a bossy woman, and she describes their disagreements as "battles." The older woman usually wins these battles, much to Scout's displeasure. Calpurnia asks Scout "why [she] couldn’t behave as well as Jem," and she also calls her home when she does not want to come in. These are all things that Scout hates. In the second chapter, Scout blames Calpurnia for having her copy chapters from the Bible in neat penmanship. Scout's teacher, Miss Caroline, disapproves of this type of handwriting. In the third chapter, Walter Cunningham comes over for lunch and Scout is rude to him. Calpurnia confronts her about it, which Scout does not like. The woman gives Scout a smack on her bottom. Scout asks her father to fire Calpurnia, but he refuses. All of these things are considered faults of Calpurnia according to Scout.

In the first three chapters of To Kill a Mockingbird, what was Calpurnia's fault?

I think that what you probably are asking about here is in Chapter 2.  That is, if you are saying that something happened and it was her fault, that's where it is.

What happens is that Scout gets in trouble at school because she already knows how to read and the teacher does not think that is appropriate.  The reason that it is Calpurnia's fault is that she is the one who taught Scout to read.

If you say "Calpurnia's fault" and you mean like what was wrong with her, Scout seems to think (Chapter 1) that Calpurnia is too strict.

What was Calpurnia's mistake in the early chapters of To Kill a Mockingbird?

In Chapter Two of To Kill a Mockingbird, Scout gets in trouble on her first day of school. Miss Caroline writes the alphabet down on the blackboard and asks Scout to read it out loud. When Scout is able to do so successfully, Miss Caroline reacts in frustrated disbelief and makes Scout read aloud most sections of the classroom textbook, My First Reader, and the stock-market quotations in The Mobile Register. Scout's natural ease with this task irritates Miss Caroline even further, and she demands that Scout not allow her father to teach her anything else at home since it causes "damage."

In reality, it is Calpurnia--and not Atticus--who is to blame for this trouble. To keep Scout out of her way on rainy days, Calpurnia would make her write out the alphabet and copy a chapter of the Bible underneath it, rewarding her with a butter and sugar sandwich if her penmanship was neat enough.  

What was Calpurnia's mistake in the early chapters of To Kill a Mockingbird?

You can find the answer to this in Chapter 2. What is Calpurnia's fault is the fact that Scout can write.  Her teacher does not think she should be able to read at this point and is upset that she does.

Scout says that Calpurnia is the one who taught her to write.  She says that Calpurnia taught her to write on rainy days.  She thinks that Calpurnia did it to keep Scout from annoying her too much -- she just had her sit down and work on her letters and copying passages from the Bible and other stuff like that.

What was Calpurnia's fault in To Kill a Mockingbird?

According to Scout, it's Calpurnia's fault that she's got into trouble at school. Apparently, this is because it was Calpurnia who taught Scout to read, and Scout's new teacher Miss Caroline doesn't think that's appropriate.

A young woman with very little experience of being a teacher, Miss Caroline is somewhat out of her depth. Wanting to prove that she can handle a classroom full of kids, she's anxious to assert her authority, and she feels that this authority has been undermined by Scout's already knowing how to read and write. As far as she's concerned, it's her job to teach Scout these things.

Scout has just had a fight with Calpurnia over Cal Cunningham's table manners. Scout is horrified by Cal's uncouth behavior at the dinner table, whereas Calpurnia chides the young lady for what she perceives as her snobbery.

As a result of their argument, Scout isn't in the best of moods and blames Calpurnia for getting her into trouble at school with Miss Caroline because it was Calpurnia who taught her how to read.