The Word "Because"

Lately, I noticed that Sharlene is fond of using the word ‘because’ to reply whenever we ask her a question. I was amazed when she first uttered this word sometime ago. She seems to be able to use this word appropriately. For instance, last night she took her school bag in the room and rummaged through the contents. When I saw her doing it, I asked:

Me: Sharlene, why are you taking out all your books? (She took out her school books and pencil case from the bag and placed it neatly on the floor)
Sharlene: Because I want to check my books. (After ‘checking’ her books, she insisted on putting all the items into her bag again). You see, she wants to take over my role now.

Another scenario in the bathroom where she refuses to brush her teeth:

Me: Sharlene, why you don’t want to brush your teeth?
Sharlene: Because I don’t like the toothpaste. (She prefers the one with strawberry flavor).

One more scenario - When she wakes up on a Saturday morning and I’m in the bedroom, she would say:
Mummy, Sharlene no school today because today is a Saturday.
Likewise when she wakes up on a Sunday morning and I’m in the bedroom, she would still say:
Mummy, Sharlene no school today because today is a Saturday. LOL!!