Aren't the ladies on this board wonderful!?! I just read this outpouring of ideas and was so struck by the love and Christ-like encouragement running throughout this thread.
I'll just add that not all ideas covered in the guides are meant to be mastered. As a teacher it took me a long time to realize that there are stages to covering new ideas. The first stage is always exposure. This does not mean that the child will master the idea or skill but is only being exposed to it. In both Beyond and Bigger Hearts, kiddos are exposed to the English grammar concepts but do not need to master them. This is true of much of the math scheduled in Beyond and Bigger as well. So, for those topics, I do the lesson and move on. I do not do additional drill and practice to make sure they "have it down". I just cover the concept as written, knowing they'll get it again.
Since you mentioned that one of your other sons had done Beyond, if you already have the Beyond guide, an easy fix would be to do only the spelling list 1 and the gentle grammar portions out of Beyond (instead of the spelling/dictation and grammar scheduled in Bigger). If you choose to stay with Rod and Staff English 2, then do almost all of it orally or on a whiteboard. Feel free to slow down as needed too but don't drill the concept. Just expose and move on.
If you haven't already tested him for his correct placement in Singapore math, I'd give the placement test at the link my3sons gave you to make sure you've gotten him placed correctly. Placement in Singapore is everything! If he tests at a lower level, place him there anyway. If you have the Beyond guide, then you can easily back up and teach the math with activities as scheduled in that guide instead. Even though the public school covers multiplication in grade 3 that doesn 't mean kiddos master it or even all understand it in that grade. Coverage does not mean understanding! So, you'll be doing your child a favor to get him correctly placed math-wise.
Also, for kiddos who have struggles with memorizing, learning the math facts is also an incredible struggle. Allow him to use a multiplication chart or an addition chart as needed to help solve problems when he's working on math. Work on math fact practice a little each day, doing only the O's in addition until those are memorized, then only the 1's, then only the 2's until you get through all of them. The Skip Count Kids CD is also a great help for kiddos who have a tough time memorizing multiplication facts. All my boys can skip count just from listening to the songs at lunch.
As far as cursive goes, I would just hold off (for years if necessary). In the scope of things, if your kiddo only ever learned to read cursive and to sign his name in cursive, he'd be fine. Cursive writing is required nowhere is life, except in a signature. A small bit of copywork done in print is much more important. Steady practice in that area will yield better results over time.
You're doing a good job of being in-tune with your kiddo and with his level of frustration. Each child is a special blessing from the Lord (with all of their unique personality traits and quirks). Our Scripture in Preparing Hearts this week is very fitting: "Lo, children are an heritage of the Lord: and the fruit of the womb is his reward. As arrows are in the hand of a mighty man; so are the children of the youth. Psalm 127:3-4.
Blessings,
Carrie