CHICAGO (CBS) — Today kicks off the first day of school for hundreds of thousands of students in Chicago Public Schools, and with the start of the new school year comes new changes.

District officials announced several changes in recent weeks, from new Safe Passage routes to redoing background checks for all employees.

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This will be the first full academic year CPS will be under the leadership of Chief Executive Officer Janice Jackson.

Last week, she joined the mayor and other school leaders in announcing an expansion of the Safe Passage program, adding three schools – including Pickard Elementary, O’Keeffe Elementary, and Deneen Elementary.

A total of 160 schools are now part of the program. The goal is to make sure students have a safe route to walk to and from school. City leaders have said crime along the routes dropped 9 percent over the last year.

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Meantime, more than 260 employees won’t be able to return to schools this year, after failing a fresh round of background checks. District officials said 57 teachers had arrests on their criminal regords, suggesting what the district called a potential history of violence, sexual misconduct, or dangerous criminal activity.

Another 245 employees did not submit fingerprints for background checks.

The district re-ran background checks on all employees, contractors, and volunteers this summer, in response to a major sex abuse scandal exposed by the Chicago Tribune.

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A new attendance policy also will be in place this year for all high school seniors. They must maintain an attendance rate of 95 percent or higher in order to be eligible to attend events like prom or graduation. Seniors won’t be penalized when they miss classes for college visits, approved school functions, or medical issues.