Singapore experts, I need an opinion

[musicianmom]

Dd6 is doing Primary Math 1B. She is still stuck on subtraction of numbers greater than 10. By "stuck" I mean that she can do the problems by herself as long as she uses c-rods. But she can't get through the steps (for example, breaking 12 into 10 and 2, subtract 6 from 10, add the 4 to the 2) in her head, she has to use the blocks. She does addition in her head with no problem. Can we keep progressing this way, just pulling out the blocks every time we get to subtraction? Or do we need to stop and focus completely on this kind of problem until she can do it mentally?

[RebeccaMary]

I know this is how Singapore presents it, but this method didn't really for my kids either. It makes intuitive sense, but it's just too much number manipulation to keep in your head.

 

Have you tried teaching it to her this way: to solve 12–6.... take away the first 2 to get to 10, then take away 4 more to get to 6. Also, if she's mastered her addition facts, she will eventually become comfortable with flipping them around to get to her subtraction facts (encourage her to think about it this way: 6 plus what equals 12).

 

Since she's in 1B, it might be worth your while to have her just go ahead and memorize her subtraction facts with a few minutes of drill every day, so it doesn't slow her down later on.

[redsquirrel]

I am a big fan of letting kids us manipulatives until they don't need them any longer.

 

But, I also talk them through the using the rods. So, I might use a 10 board, showing how they got to 10 first and then did the subtraction. I often narrate what I see happening with the rods or base 10 etc. I might say something like, "ok, I see what you are doing here, you are getting to ten.  Good, because that is how you do it. Can you tell me what the next step will be?" Or if there isn't any getting to ten, then I would say "This is how I would do it. (demonstration with narration) Can you do the next one the same way?" I have found that if he is having to narrate and explain what he is doing and why, every single time, it becomes a whole lot easier to just use the numbers.

 

I also sometimes let him use rods and sometimes base 10 blocks. I think using different manipulatives can be useful.

[cintinative]

My youngest got stuck at the same spot. We took a break from the book/workbook and just did work with the regrouping using an abacus and other manipulatives like the base 10 blocks and unifix cubes. We did that for maybe a week or so until I felt like it was getting old, skipped to a geometry section (shapes) and then went back to it, and he was fine. We also were working with subtraction flashcards, albeit slowly. I am no expert, but it seems this may be something that just has to click and then the rest will come easier. I do think the abacus helped, but my son is very tactile. Also, I got it for $2 used so I didn't waste a lot of cash to get it. You could use m&ms, beads, etc. for the same purpose.  

 

All that to say, I am no expert, but don't feel bad about "parking" in this part for awhile and trying a lot of different methods to get the concept across. 

[Crimson Wife]

I have used both Right Start and Singapore and this is one place where I think the Singapore method is unnecessarily convoluted. Personally, I prefer the RS method of breaking 6 into 2 and 4, then doing 12 - 2 = 10, then 10 - 4 = 6

[three4me]

We have had trouble with this. Now DD's got it down within 20 and we're having a hard time translating that to subtracting from larger numbers. Basically how I helped her get over the first hurdle was to have her repeat after me. 13-9=...  "You can't subtract 9 from 3, but we can subtract it from 10. So 10 minus 9 equals 1, then we add that back to the 3 which is 4. So 13 minus 9 equals 4." So now when she comes to a problem like this she automatically says this out loud. It just helps her talk herself through it and has become very helpful.

 

In the end, though, it just has taken practice. Now that she's getting stuck subtracting from 20+ we're just going to hold off on moving on until we've worked on this for a while. She's been using c-rids and linking cubes right now and I'm sure she'll eventually be able to understand the concept mentally.

[Tanikit]

It took my DD into Singapore 2a to really be able to manipulate the numbers well enough to do these sums without manipulatives - as long as she could show me with the manipulatives what her thinking was I knew she would eventually do it by herself and I felt fine to move on. But then we are using other curricula with Singapore which gave her a bit more practice at times and also meant that she spirals tighter than what Singapore alone would give her which is why I am less worried about mastery immediately. 

 

She is now quite capable of doing the subtraction with both methods listed and doing it in her head. Just be patient and keep reviewing if you do decide to move forward.

[tabinfl]

Got stuck at the same spot here. Out of desperation, I sprung for Math Mammoth. It worked!

 

It took longer, but the smaller, more gradual steps really "stuck" especially for my son, who was having the most trouble with the SM stuff.

 

Not sure if/when we will switch back.

[sarasue7272]

My son had a hard time with this, too. I used dimes and pennies and made change. I have 13 cents and want to buy something for 7 cents, I wouldn't pay with all 13cents, just the dime. So I get three pennies as change and still have my original three pennies. This follows that method pretty well and it really helped my son understand those ones that are kind of hanging out on their own.

 

Now, in real life I might pay with all 13 cents (so I could get a nickel) but that is a lesson for another day.

[Steven]

As I recall when we did this (we are now is 4B), I made the manipulative suggested in the Home Instructor's Guide: Multiple egg carton cut down to 10 eggs, and some sort of counting items. We used little glass jewels (they don't roll away like marbles). 

 

So 13 was a tray of ten plus a tray of 3. Then in another tray, we would move over nine counters from the tray of ten, and finally consolidate the two partial trays.