There are a few different reasons that a child may respond in this frustrating manner, so before you give up asking her questions, consider the following:
1. Perhaps she is afraid she will get in trouble if she answers honestly (do you yell and punish a lot?)
2. Maybe she has a difficulty processing or comprehending language and questions are confusing for her (she may need a language evaluation to make this determination). Saying "I don't know" is a frequent response for kids with language based learning disabilites because they don't want to admit they are confused or didn't understand the question.
3. Maybe she is angry with you for something unrelated to the questions you are asking; saying "I don't know" could be a passive way of expressing anger, rather than making an effort to respond to you (is there any upheaval in your family right now?)
4. Perhaps she hasn't been challenged to respond to questions in a more productive way and needs you to begin helping her along--patiently.
Good Wishes and Great Parenting,
Dr Susan Bartell
JustAsk Expert www.drsusanbartell.com
NEW book "The Top 50 Questions Kids Ask"