Do you have a sticky exercise problem that neither you nor your child can figure out but really need to? Now? Check first with your curriculum publisher (Apologia is super to work with). But if the curriculum publisher offers no help, there are a number of homework help sites, some free, some for pay.
We've not used any of the for pay sites, but they might have been nice once or twice in a desperate moment especially during the high school years.
The Beehive This site offers Homework Help. Click into the appropriate grade level (Elementary, Middle School, or High School) and a menu of subjects appears. Choose your subject, and a long list of helpful sites appears. These are mostly supplemental support sites rather than "ask a question/get an answer" site...but there's a LOT there and geared towards free information. Some sites listed (such as a favorite of ours, Dr. Math ) allow you to post a question and get an answer, for free (albeit not responded to immediately).
SmartThinking.com is another for pay online tutoring site. You can pay by the hour ($35) or buy more hours in bundles. Tutoring is done through an online browser experience similar to the online customer service chat many companies use. The nice thing about this site is that you can submit single written essays, including a SAT essay example, and have constructive feedback and grading. Essay evaluation prices are from $10 to $20 per essay, depending upon length. Click on "Individual" and "buy now" to see prices and subjects offered.
Tutor.com Direct. This is a large firm out of New York. It offers help in subjects in math, English, science, and social studies for grades 4 through 12. The nice thing is it offers promotionals where you can get the first 60 minutes of consultation for $5. After that you can pay as you go with a one-time rate (beginning with 60 minutes/month for $35) or pay monthly (beginning $32.50 per month for 60 minutes with rollover minutes up to a year). Tutor.com states you may cancel at any time. No hidden fees. Tutors are experts in the field.