On dec 20, 2015, at aproximately 9:00 pm, me and my neighbor who lives right next door to me we're out in the back talking when I looked up and noticed some beams of light in the sky right above our house is now these lights weren't high they were pretty low that's what caught my attention and my neighbors attention the lights seem to move very erratically back-and-forth, forward and backward, stopping ,blinking, moving in circles, at a high rate of speed, the lights also seem to be moving in formation we managed to take pictures and catch some on video! At one point the lights seemed to stop and just sat there in the sky Above our homes for a good I would say 4 to 5 minutes and then they seem to meet back at a certain spot and then the lights started blinking and flashing while the other lights did not!there had to be a total of about anywhere from 7 to 9 lights!!! And then when they were finished one by one they shot off at a high rate of speed heading northeast from our position towards Lake Michigan!!!! We've noticed a lot of activity in Berwyn but this by far was the craziest!!!!