Diana,
This is a short blog post, not an exhaustive discussion of credits. For more information, try this free class:
A Homeschool Parent’s Guide to Grades, Credits and Transcripts
http://www.thehomescholar.com/homeschool-transcripts-webinar.php

If you would like more assistance, I have written an entire book about high school records that I think you will enjoy, and it will give you the long detailed information.
Setting the Records Straight: How to Craft Homeschool Transcripts and Course Descriptions for College Admission and Scholarships
http://www.amazon.com/Seltting-Records-Straight-Descriptions-Scholarships/dp/1449583555

Parents don't need to use curriculum, or use a curriculum guide for all of their classes, nor do they need to be guided by the state to judge what the child has learned.

Blessings,
Lee

I think it's misleading to believe that logging hours is the only criteria to judge whether one has acquired the material for a course. To judge if one has learned material, I think the parent should use a curriculum guide for what should be learned (according to the state). Then, regardless of how many hours are logged, if the parents test, measure, and document the material that should be sufficient.
For example, if a homeschooled child learns Algebra 1 in a 7-month period, why shouldn't the child go on to geometry. Does anyone really think that a college cares whether a child has logged 180 hours with an Algebra book.
Besides, so much time is wasted in the classroom that those 180 hours are not all spent learning. I think it's better for the child to learn the material, apply it in some manner, and move on to the next learning experience.

Heather,
The parent knows best - how much the child is doing everyday, if they are adding supplements, if the child has a learning disability, etc. A high school credit can be lower level work sometimes, depending on the situation. My free class on credits will help! You can share this with a parent, when you aren't quite sure, and that way they have to do the research to figure out if it is legit. Here is the free class:
A Homeschool Parent's Guide to Grades, Credits and Transcripts
http://www.thehomescholar.com/homeschool-transcripts-webinar.php
Blessings,
Lee

slightly related question, what do you do if someone is using "your" class as a credit and you don't think it's worth a full one? I'm teaching a "middle school level" environmental science course, as requested, but one of the people requesting it has her 9th grader enrolled as his total science credit for that year. It's a 20 week, 1 hr per week class that will have approx. 2-3 hours of homework a week. I suppose it's her decision, but I feel like I'm involved in cheating!