Falls Church School Superintendent Dr. Toni Jones told the School Board at its work session tonight that enrollment in the City schools is expected to increase at all levels once classes begin next Tuesday at an overall rate of 3.5 to 4 percent over the numbers when classes ended in June. “We are scrambling now to find ways to keep class sizes down,” she said. At Thomas Jefferson Elementary, for example, she said, they are completely out of classroom space as of now. “The only thing we don’t really know yet is how many students from last spring may have moved away over the summer.”