During my earlier schooling there were many single stories. The stories could have taken place over seas or take place here in Canada. What is problematic with the use of these stories is the bias they create by providing only one perspective or lens. By doing this we are really limiting the students' exposure to new things and ideas. "Whose truth mattered?" - It seems like by allowing all these single stories we are putting an emphasis on the dominant white privileged society. As these stories are generally shared through their lenses.
Growing up I always attended schools in good areas and never had to worry about such things as my safety or whatever it may be. I had a privileged life growing up in a stableish family setting. So my perspective was fairly limited. It wasn't until my parents got a divorce and my mom who moved out to a low income housing area that it provided me with a new perspective. It wasn't until this happened that I tried to consider more perspectives. This event, even though it may have been short lived because my mom moved to a "better" area in a couple months. Really had a positive impact on me and changed my lenses.
Depending on how you were raised is going to have an impact on your lens. It is important that you recognize your lens and biases when you go into a classroom so you don't pass on those biases to your students.
"How might we unlearn / work against these biases?" Just recognizing your biases is key to work against them. If you fail to admit that you may have biases there is no hope in over coming them. Then you should try to increase your knowledge by trying to read up on others perspectives maybe. Even though it may be weird at first. Trying to see the world through different lenses/perspectives does help a lot.