The nature readers from Christian Liberty Press are good for elementary science. My kids read them once a week and do nature study with nature notebooks once a week. They will do more science in 5th grade.
Composer study is very easy to work in. Read aloud a short bio. first or use a disc like Vox Music Masters or Klassics for Kids. I look forward to listening to the relaxing music everyday at lunch. I have grown to like it and play classical music in the evenings some too. Pick a composer and have a few of their music discs or get mp 3 sets for $2 @ Amazon:
http://www.amazon.com/Beethoven-Supreme-Classical-Masterpieces-Masters/dp/B005W26W12/ref=pd_sim_dmusic_a_10
As for working in these extras, go slowly, adding one subject at a time until you are comfortable with it. Here is a post that helped me:
http://simplycharlottemason.com/basics/started/transition/
We use Hymns for a Kid’s Heart. It is easy open and go, and about 5 min. each time.
As for being overwhelmed, I have been there; still go there some days. There are several books which have helped me, but I have come to know how important a daily quiet time in the Word is. It is important for me to know what *He* wants me to accomplish each day, not what *I* want to accomplish. I was doing a lot of cleaning myself and have come to realize that my children not only are capable of helping, but that it is GOOD for them. This is an excellent way to work on character training. So I have been teaching them new tasks while reading about chore systems so I can get the right system set up for us. For this I have been reading Vicki Bentley ‘s chore book and I am reading a great book on organizing my day which includes a chapter on chores, Managers of Their Homes by Teri Maxwell. She also has a book on chore system called Managers of Their Chores. They are at Titus2.com.
Another huge help is to get a menu plan set up to follow. This can rotate weekly, bi-weekly or monthly and can vary for each meal. I do bi-weekly M-F for lunch and monthly for supper. I am working on breakfast now. I have also found Large Family Logistics to be a good book for ideas on managing the home, and imho, “large” is greater than one dependent, for most things in this book.
I will leave you with a few quotes from my notes from the Maxwell book:
“The goal is to eliminate as many decisions as possible – since decisions take up much of your time and emotional energy.” page 52. If I have chore systems, menu plans, and schedules in place, I make the same kind of decisions much less often as they are made when creating the system. Now I have to decide to follow the system I created and prayed about. It is very important to keep the same wake-up time and meal times, something I am still working towards. It is a marathon, not a sprint. And limit computer time.
“A schedule is your plan for your family for your particular needs. It is like a puzzle with many little pieces that need to be meshed together for the greatest efficiency of your home.” page 103.
“Most of the chore issues are character related and are where I want my focus to be.” page 99. When children fail in their chores, see it as character training and calmly deliver the pre-posted consequence, like doing the job again in your free time. Be consistent in inspections, training, and discipline. Vicki Bentley says, “Children do what you inspect, not what you expect.”
I have also been working on getting my children more independent in their learning. I have read Joanne Calderwood’s The Self-Propelled Advantage. She also has a website at urthemom.com. This can work with CM methods. She stresses the importance of good character training as a prerequisite. SCM Laying Down The Rails is a great resource if you need to work on character and good habits. Again, it is a marathon. Their free ebook based on good habit training:
http://simplycharlottemason.com/store/smooth-easy-days-with-charlotte-mason/
I am not an affiliate to any of these books, but have found them all to be helpful to me. I hope something here may be of help to you.