Ashlee Rezin Garcia/Sun-Times Chicago Public Schools and the Chicago Teachers Union have landed a tentative agreement to reopen high schools, setting the stage for thousands of teenage students to return to classrooms Monday for the first time in more than a year. The deal will still need to be approved by the union’s 25,000 teachers and staff. The CTU’s House of Delegates — its 600-member governing body — is set to convene Thursday afternoon to review the terms of the agreement and potentially set up a ratification vote by the full membership this weekend. A CTU committee of rank-and-file teachers and staff who have been involved in bargaining has recommended approval of the agreement, the union said.