Hi!
Is your son college-bound? IF not it doesn’t really matter how you do this. If he might have college in his future, it’s a little more complicated.
Algebra: I did not count algebra done prior to 9th grade on my sons’ transcripts. You really don’t need more than four credits of high school math. Since my sons did algebra in middle school and are now in calculus and pre-calculus, I’m just listing the last four high school level credits (calculus, pre-calculus, algebra II and geometry.) Algebra in the college-bound world is really a middle school class–that’s when both my sons, dh and I took it.
Physical Science is likewise really a middle school level class.
If you do other things in addition to Penny Candy, I think you could add that to the other items you do for an Economics credit, but you’ll need more than the one book. I would list what year it was read–even if you make a transcript by subject and not by year, you are going to run into folks that want it listed by year as well–I had to do this for National Merit and also for some schools we applied to.
History reading, you are going to want to try and figure out exactly what you want to have for credits, which normally involve about 120 hours of work. I figured out that we probably weren’t putting in enough work to end up with more than two high school level credits, over the four years, which was OK, since we did lots of other social science, so I just collected all the stuff we did, divided it up between World and American and called it good. 🙂
I would start keeping a running list now of all that you do that might apply to credits–movies, papers written, books read, everything. You can divide it up into classes for now if you like and you can always change things around later–I’ve done this.