CHICAGO — School bus aides are among the support staff members who are taking part in the Chicago Public Schools strike, which is now in its eighth day.

Approximately 32,000 teachers and aides went on strike on Oct. 17, and about 7,500 of those are support staff, USA Today reports. School bus aides, who are represented by the Service Employees International Union (SEIU), said that pay is the main issue driving support staff to participate in the strike, according to the newspaper. More than half of the school district’s support staff members earn less than $35,360 a year, and bus aides earn, on average, $15,759 a year, according to the SEIU’s Facebook page.

The Chicago Teachers Union (CTU), which is leading the strike, is primarily calling for smaller class sizes, better pay and benefits, fully staffed schools, and “justice for families,” which includes sanctuary schools and sustainable community schools, according to the union’s website.

The CTU and the Chicago Board of Education reached tentative agreements on Wednesday on dozens of the union’s individual issues but not on its top priorities, the Chicago Tribune reports. The Chicago Board of Education has offered teachers a 16% raise over the course of five years, while the union has asked for 15% in a three-year contract instead, the newspaper reports. In addition, the Board of Education is offering to invest millions of dollars to lower class sizes in high-need schools and to support homeless students, to put into place a sanctuary schools policy, as well as provide a full-time nurse and social worker for every school, according to the Chicago Public Schools Facebook page.

Meanwhile, classes were canceled again on Thursday for the district’s over 350,000 students as the district’s Board of Education and the union continue negotiations.