Carrie and I just talked through your questions, and we both think that the best plan is to continue RTR for 7th grade, to do RevtoRev for 8th grade, and to then look at the placement chart at that point to choose either MTMM or WG for 9th grade, whichever is the best fit overall. This will give you only one decision to make, and it will be clearer which placement is best when you reach the point of your ds entering 9th grade.
I will still answer your questions below though, as MTMM can quite easily be done for 9th grade should you decide at that point it is the best fit for ds.
Ds is due to begin Rev 2 Rev in 8th grade, which he begins in June. Just to be sure I understand, we would complete Rev 2 Rev as written. Then the following year he will begin MTMM in 9th and I would need to add to the economics already written in the plans. He would then have 1 credit in American History and 1/2 credit in economics. Correct?
That is correct.
Carrie had this to say that makes it clearer how you would do this...
In looking at Economics, you will want to keep in mind that you are typically looking for only 1/2 a credit (or a semester) or Economics for most state (and college) requirements. With this in mind, you would either want to add the Bluestocking Guide and its related material to MTMM OR do Notgrass Economics OR do R.C. Spoul Jr.'s course including his book Biblical Economics OR do Sproul Jr's DVDs (Economics for Everybody) along with the supplemental reading material suggested in the booklet that comes with the DVD. If you use Hazelett's, you would most likely add that to the Bluestocking Guide option. Otherwise, the other options will be enough without Hazelett (especially now that R.C. Sproul Jr. has added a guide along with Economics for Everybody DVDs to help add supplemental reading material to get the hours needed for the credit). If your state does allow the Finance OR Economics option, then you could also entertain the idea of doing Financial Peace University with Dave Ramsey in place of Economics. With our son, we actually had him do both Economics and Finance just because we thought both would benefit him. We did Notgrass for Economics and Dave Ramsey and Larry Burkett both for finance. Economics and Finance were not both required for our state. Our son earned a 1/2 credit in each course.
Would I need to add "The American Testimony DVDs" from the extension package?
The target age range of MTMM is for ages 12-14 years old, and the extensions are for 9th and 10th grade. So, yes, he should do the extension package, and he can then claim 1 full credit in American History. The clep test for American History itself is in 2 segments, so you doing 2 years of American History in 2 segments (i.e. American History 9th grade in MTMM and American History 12th grade in the upcoming AH guide) is just fine!
Now how about science? Do I need to add Chemistry 101 DVDs? Honestly, I don't even know what those are or who is the publisher. I just read it on one of the older threads about beefing up MTMM 
. Will these DVDs along with the science as written truly be equivalent to high school chemistry?
Carrie had this to say in another thread that should help...
You can use much of the Missions to Modern Marvels science plans "as is" with a child in the extension range by using Ellen McHenry's Carbon Chemistry in place of Evolution: the Grand Experiment and the Genetics & DNA kit. This would give your high school child a full year of chemistry, and Carbon Chem. is designed for use after "The Elements", so it would work well in place of Evolution: the Grand Experiment. Additionally, you could also consider adding the new Chemistry 101 DVD on each 5th day, watching a segment each week (and also possibly pursuing some of the suggestions for lab work that come with the CD). This combination along with what is already scheduled within the Missions to Modern Marvels guide would raise the coursework to a high school level science while still keeping the living books approach.
Just google Carbon Chemistry by Ellen McHenry, and Chemistry 101 DVDs by Wes Olson. If your ds is not going into a STEM career (science, medical, engineering), this science is fine for his 9th grade year.
Would I also need to beef up English? He would be in Rod and Staff English 7 in 9th grade. Is this sufficient or would we also need to add a composition component?
The first half of R & S English 7 is what is scheduled in 9th grade HOD anyway, so he'd be right on track! The composition component in MTMM of WWTB 2 is already high school credit worthy, so you would just do that as scheduled in MTMM.
Then there is literature. He would have completed DITHOR 6/7/8 at the end of 8th grade. So when he begins MTMM for 9th, what will we do for literature?
You would use DITHOR for 9th grade with high school titles. We have posts on this and can help when you get there.
There are many options for science that I won't get into here, but basically you could do the science from any guide alongside whatever core guide you are using if you want to just use plans for 9th grade as they are written. There is also the option earlier on of having ds do the Advanced EE Kit in his 8th grade year for a high school credit in physical science. However, let's not jump the gun! We'll know better when that time comes! I hope this helps, but just remember, doing RTR for 7th, RevtoRev for 8th, and then reassessing to choose either MTMM or WG for 9th is a wonderful plan moving forward!
In Christ,
Julie
. I've searched the board and found lots of posts on the topic and I have to piece it all together, which became overwhelming after the first hour 
but has anyone skipped Rev to Rev or MTMM? Skill-wise they seem pretty similar so I am tempted to skip Rev to Rev, particularly since dc could handle Rev to Rev now 
This is my main reason for considering skipping Rev 2 Rev and just doing MTMM for 8th and WG for 9th. I have a great set of books that tell history in story format so we could read over the missed time period from Rev 2 Rev during the summer before 8th grade (we school year 'round). Sure, this would not give us the depth that HOD does but he would get that year of US history again during the high school guides. Does this sound crazy? According to the placement chart, ds can handle Rev2Rev now in 7th. What would be the effects of skipping Rev 2 Rev and going into MTMM for 8th?