You might want to check out Virtual Homeschool Group. From their website: “Virtual Homeschool Group is 100% volunteer-run. We have been serving free ‘at your own pace’ (ayop) and live online courses for home school families for 11 years.”
We have used their classes for General Science, Physical Science, and Biology — all using the Apologia textbooks. You can take a live class at scheduled times each week, or you can sign up for an “at your own pace” class which has recorded lectures. We used the AYOP voicethreads for each module where the teacher gives a lecture to accompany slides pertaining to the information. There are quizzes and exams for each module, and the grades are tracked for you.
Did I mention that the classes are free? You just need your own textbook, and you can either do labwork on your own and turn in a lab sheet to be grades, or you can find a separate lab class offered through a co-op or some other way. Fortunately, the co-op we’ve attended for years usually offers biology lab session one year and chemistry the next, with physical science lab sessions offered whenever there are enough students to take them.
Here is the link to Virtual Homeschool Group: http://www.virtualhomeschoolgroup.org/. They offer other courses, too, in math, language arts, social studies, and foreign languages. Not all courses are high school; some are middle school.