It is significant for Jem and Scout to be sitting with Reverend Sykes at the trial. Sitting with the "colored" people offers Jem and Scout an opportunity to a different perspective:
This gives Jem and Scout the perspective to feel what the colored folks feel. Jem believes that both these races should be equal and get along.
Also, by sitting in the balcony, Jem and Scout show their support for the races being treated equally. It is strong statement to what Atticus has taught his children. Jem and Scout did not think twice about sitting in the balcony with the "colored" people. They are very comfortable sitting in the balcony with the "colored" people. In fact, Jem and Scout would be the first to argue that there should not be a separation of the races anywhere but especially in court.
No doubt, Jem and Scout better understand how "colored" people feel having to sit in the balcony apart from the white people. It is humiliating to think that one is considered less because of his or her race. By sitting in the balcony, Jem and Scout can feel the distinction between "colored" folks and white folks. They are reminded that life is not fair for folks of color in Maycomb.
In Chapter 16, Scout and Jem attempt to get a seat on the crowded courtroom floor and seem to be out of luck until Reverend Sykes notices them standing against the staircase wall. Reverend Sykes then walks up to the balcony and comes back to inform the children that there are a few seats open for them in the colored section. Jem immediately agrees to sit in the colored section, and the children watch the trial from the balcony. It is significant that Jem and Scout choose to sit with Reverend Sykes because it illustrates their tolerant, accepting nature towards people of different races. Atticus has raised his children to treat everyone equally and accept everybody regardless of their race. Jem and Scout's perspective towards African Americans is unique in the prejudiced community of Maycomb. Sitting in the colored section demonstrates that Jem and Scout are comfortable around African Americans, which is relatively uncommon for white people living in the Deep South during the 1930s.