The Seattle Public Library joins the King County Library System in offering free online tutoring help for students in fourth through 12th grade in math, science, social studies and English.

The Seattle Public Library requires a library card to access the Tutor.com service, while King County does not. Seattle's access (www.spl.org, then select "Homework Help") is available from 3 to 10 p.m. daily; King County's (www.kcls.org/homework) is open from 2 to 10 p.m. daily for up to 20 minutes a day. Professional tutors help students work through problems in a real-time chat.

King County librarians (and a contracted service when local libraries are closed) also answer homework questions in a live online chat 24 hours a day, every day. A library card is required for this service.

Both library systems offer drop-in, one-on-one tutoring by volunteers in selected branch libraries on weekday evenings. For a list of King County locations and hours, visit www.kcls.org/studyzone; for Seattle, click on "Homework Help" from its main page.

Stephanie Dunnewind, Seattle Times reporter