First why

Penny has now used the word "why" twice. I read somewhere that why was a hard concept to grasp, and it makes sense to me because I can't define the word why. So, whenever I would ask Penny why something, I would immediately follow the question with a rephrasing of it using another word. Like, "Why are you scared, Penny? What made you scared?" I was hoping that would help her figure out what why means. Well, one day this week she was standing on the stool in the kitchen helping me make something and she turned toward the sink. She reached in toward the dirty dishes and asked if she could touch them. I said no. She said, "why not?" (In a really cute toddler way.) And so I explained why not. Then today on the way home from the playground she was eating crackers. She said in a mischievous voice, "is my carseat clean?" I knew that meant she had crumbled the crackers everywhere, so I said, "I'm gonna go with probably not." She said, "and why not?" (I said, "because you got cracker crumbs all over it." She said, "yeah.") I think it may be awhile before she asks why all the time, or about things she doesn't already know the answer to, and I'm sure I'll get tired of it one day, but I think it's cool that she made the leap to "why."