First, thank you for creating a democratic forum for this discussion.
I am a parent and a professional educator. I am excited and embrace the longer school day. It is good for both of my children, who are CPS students and as an educator, it is the right thing to do.
My greatest concern is that recess and any kind of physical movement during the school day is greatly limited. I cannot support a longer school day if the absence of recess, PE and related opportunities for students to run and play continues to be limited.
The work of nueroscientists like John Medina (his book is Brain Rules) cite significant science that limited or no movement actually stifles learning.
Recess, PE, art, music, drama are not "extras", they are essentials because they prepare our brains for learning in reading, writing, mathematics, science, and social studies.
Build the Longer School Day WISELY.