Educators in Charleston County’s lowest performing schools are in a race against time: Turning things around before another class of undereducated children makes its way through the system.

Three of those schools — Hursey Elementary, Morningside Middle and St. John’s High — have made notable progress, and are no longer considered at risk.

Their achievements are commendable and should demonstrate to educators that the difficult task of saving a failing school is possible.

Their success also should demonstrate to parents that they do not need to tolerate schools that fail their children.

Sadly, of the 21 South Carolina schools that continue to be classified as “at risk,” five are in Charleston County: Burke, North Charleston and Stall high schools; Burns and Sanders-Clyde elementary schools.

And while Charleston County School Superintendent Nancy McGinley gives partial credit for the successful schools to federal School Improvement Grants, some of the schools that didn’t move off the at-risk list also received funds. That should be of vital interest to the Charleston County School Board as it considers the superintendent’s request for a tax hike.

The district should be able to explain how the money helped Morningside Middle and St. John’s High schools improve, but failed to have a similar impact on Burke, North Charleston and Stall. And how could Hursey have made significant progress without the grant money?

Dr. McGinley said she’s hopeful that North Charleston and Stall will move up this year. And since some of $2.3 million, three-year grant will run out in September for North Charleston and Morningside, eliminating pay for as many as 12 staff members, she is asking the board to approve $400,000 for the coming school year to save some of those positions.

Board members have said they need to be convinced that a tax hike is necessary. They should also be convinced that the $400,000 will improve education.

The board already has approved extra pay for teachers at four schools, including Burns and Sanders-Clyde, to provide them with additional training.

It would be unkind to throw cold water on the fine progress of Hursey, Morningside and St. John’s. But it would be short-sighted not to point out that there is still more progress to be made in those schools, too.

And other schools not on the at-risk list have been given grades of D and F. They need the district’s attention as well.

Further, plenty of parents would agree that a score of C isn’t good enough either.

Dr. McGinley has put a lot effort into addressing the needs of the district’s lowest performing schools.

The race is a marathon, but the district needs to run it at the speed of a sprint so that more students will not end up without a quality education.