The Grace F. Cole Elementary School, with a projected enrollment of 106 fifth-grade students, is hiring another teacher for that grade in order to meet the demands of the incoming class. Meanwhile, 104 students will be divided into four classes at the William G. Vinal School, which will create a larger class size: an average of about 21 at Cole, compared withabout 26 at Vinal. To bring things in balance, the district is holding a limited open enrollment program for all Grade 5 students from the Vinal attendance area. The program, which has an Aug. 1 registration deadline, allows for voluntary transfers for these students to the Cole School until class sizes reach a balance of 23 students per class.