If I decided to teach both children from the same level such as Science, History..etc What level do you pick? DD is finishing up 5th and DS is finishing up 3rd.
I guess it depends on your kids. I think it is generally easier to go with the lower level and add to it for your older child.
I would have to say my ds who is 2 yrs younger, masters new skills better however, dd is a straight A student still. DS so far when I run assessments, will be in a higher grade level for his age while DD is right on track. I guess I would lean to getting the older one and work with him more if he seems to struggle.
There are programs designed for multi-levels. I did Considering God's Creation (a science curriculum) when my kids were grades K, 3, and 5. It would work well for the grades you have. Also, I use The Mystery of History with all my children at once.
I would go for the higher grade level but not expect as much from the younger child IMHO, but it would depend on the children. It is usually easier to take away material than to find material to add.
I agree with Sue May. I found it better to use material ready for the older and teach it to the younger one as well. I have also used Considering God's Creation and Mystery of History. They are set up with helps for instructing multiple ages. Your kids' ages would fit nicely in either curriculum.
If you had to pick a grade level, I choose 5th grade if your kids are going to be the equivalent of 4th and 6th grades next year. Since you know best how your kids learn, you could choose different methods of assessment but use the same text and materials.
Tapestry of Grace is multi-level as well! Both your kids would probably be in the "Upper Grammar" level but you can assign them different writing level stuff if you used their "Writing Aids" program (which I personally am starting to really like considering Alexis just wrote an excellent paragraph telling the basics of how to make a mummy - ok the line about wrapping the body in linen so you didn't have to see the body get all yucky was kinda funny)...
I did this with my children this year. My oldest is doing 5th, my middle is doing 3rd. We used Abeka 4th Grade History as our core b/c I wanted to teach American History. I expect more from my 5th grader, obviously. It's challenging to my 3rd grader, but he's holding his own and not getting frustrated. With each chapter we're doing a read-aloud that fits that time period. When I come across one that I want my daughter to do that is a higher level reading, etc. We just do different books. My son will do one more his reading level, and my daughter more hers. She and I just finished up "I Am Regina" a couple weeks ago. What a great book! LOL Anyway, I will be doing this again next year using Abeka's Old World History & Geography as our Core (think that's 5th grade). And adding historical fiction to match what we're learning. It's going to be a challenge for my son, but I'll work more closely with him on it. HTH. (oh...and 2nd recommendation for Considering God's Creation....that's a great multi-level Science)
In that past for us (my older two have a 2 year span). Things my older dd was into my younger had really little interest in, regarding history. For example I noticed this more so when we used a Sonlight Core last year. FIAR for unit studies was nice for them to share, but because of the age of my younger, some of the book selections were things just didn't appeal to her even in that format. This year I just do SOTW out loud to them at a meal twice a week and they both seem to enjoy that though. My 3rd grader also reads her own history to herself (just living books from various sources, Sonlight, Robinson curriculum, etc). Also they share science. Right now my 3rd grader reads it out loud (using The complete book of animals). This was just something about animals that they both enjoy hearing about. I read a Burgess book to them twice a week. And also my older dd does her own science reading as well. As you can probably tell. I like to read but not be the sole source which is why my older dd does her own reading of these topics in additional to our joint time. I've learned for our family, that I don't like the confines of topics or read a bit of this or a bit of that, as had been the case with some things I've used in the past. From this year on, in my pencil plan, my view point is that we are to use the Robinson reading list (which is by age/reading level), our own selections and some of the Sonlight books mixed in. So far this has been a good happy mix without bogging any of us down. Much luck finding a good fit for your family.
