New at classical learning and asking for feedback for Science

I have three children. This year will be our first year in classical learning. I have a 14yr old special needs child who learns along side his 7yr old sister. She is considered 2nd gr which they both will do. My middle child will be 10 in 4thgr studies. I was considering Apologia Astronomy because they all have an interest and excitement about space. But my husband will teach this with them in the evenings 2x’s a week. He travels and this will incorporate time with kids and interest in their studies/learning.

> I want to do 106 days with all of them. Will I need CGC for my fourth grader? We will be doing intensive Language/grammar/spelling/writing because I found alot of holes from the public schools (we took out my oldest special needs child last year and my middle child out 2yrs ago). I dont want to over whelm my 4th grader but have him really enjoy learning and this science as a family sounds wonderful. Im afraid if he is to be asked to do extra I dont want to push him too much when he professes to be an “inventor” and “creator” but hates to work.