In my experience, it is. I went to a Sci/Tech magnet school, and it still never came up. The 'correct' answer is always either yes or no; 'I don't know' is not

In my experience, it is. I went to a Sci/Tech magnet school, and it still never came up. The 'correct' answer is always either yes or no; 'I don't know' is not acceptable in a paper or on a test. At least they were good about generating your own conclusions, and not just trying to make your observations fit with what the teacher thought they ought to be. Most of the time.