The St. Paul Public Schools hired a private firm this year to take on the daily challenge of finding substitute teachers, but its struggle to fill absences -- an issue first reported here in October -- continues.

An update presented to school board members this week showed that Teachers On Call filled a smaller percentage of substitute slots in each of the first four months of the 2014-15 school year than did the district when it managed the substitute teaching pool itself a year ago.

The percentage of absences filled by Teachers On Call dropped steadily, from 88 percent in September to 82 percent in December. The district's daily "fill-rate" goal is 90 percent. When classroom absences go unfilled, teachers are more likely to be pulled back from training sessions or principals required to employ creative measures such as rotating in other teachers with time available during a given day.

Superintendent Valeria Silva noted that the frustration of finding substitutes was not unique to St. Paul. As to whether the district is "worse off" now than when it managed the day-to-day operations itself, Laurin Cathey, the district's human resources director, said that he could not say, especially given that requests for substitutes also has been greater each month than it was in 2013-14.

The need for teachers to receive iPad-related training has contributed to the number of daily openings, but illness remains the biggest factor in teacher absences, Cathey said.

"This is the year of the flu," added Silva.

The district now is weighing whether to have teachers who now are on special assignment serve as substitutes in the spring, Cathey said. He also is considering hiring 15 full-time substitute teachers for the 2015-16 school year. What he's not about to do is call for an end to the Teachers On Call arrangement. Cathey told the board he wants to continue working with the firm to build the substitute pool.