What is it?
We love to be right. It is easier. In the past, we only made survival-based decisions. Which confirmation bias really helps out with! Now, we are receiving enormous amounts of information and our brains have to cope with it.
Something else we now have, are beliefs. Confirmation bias allows us to believe in our beliefs...no matter what.
In order to help ourselves deal with confirmation bias, you need to do a couple things. Number one, acknowledge it´s existence and that you are not some sort of super human that it does not effect. Number two, try and falsify your ideas. Falsification is the act purposefully trying to prove your ideas/beliefs to be untrue.
"What the human being is best at doing is interpreting all new information so that their prior conclusions remain intact." -- Warren Buffett
Think of a belief or an idea you have in regards to teaching or your students. Now, try and design an assessment that might prove you are wrong. (If you are not able to design one, that might be an indicator that your idea or belief is not based in science.)
Now that you have the assessment...Give it! Pay attention to ALL of the data, and determine if this assessment proved your idea false. If it doesn´t, you can always try and think of another one... The more we go through the falsification process the better!