The minimum fine for school zone is $150. And it's a required appearance (you can't just sign the ticket and send in the money). The judge could increase the fine. You cannot get supervision. They treat school zone speeding seriously.
The offense is not supervision eligible and conviction will result in suspension of your DL. You need a lawyer. The bond was required because of the minimum fine of $150.00. From the $150 you posted, 10% automatically goes to the clerk of the court. The remaining $135.00 can be applied to your fines and costs or assigned to an attorney as all or part of his/her fee, at your option (assuming this is a Cook County case). You should talk to an experienced criminal defense/traffic attorney. Most of us provide free consultations. www.galivanlaw.net