Teaching Subtraction (1st grader)

[dietmom]

My DD is not homeschooled--but is at public school this year. I homeschool my oldest son who has really never needed much math instruction--especially at the basics level--he could just do math in his head. So, that being said, I never had to teach it--and now my DD is just struggling to learn subtraction. They adopted Singapore this year--but she doesn't seem to get the 2-step processes and tricks yet. Her teacher is really pushing them to not "count" or use their fingers to do it--which she can do--so tell me some tricks you have used to help with teaching subtraction and helping kids to just "know" it rather than having to figure the problems out every time--it just takes her forever!!

 

I'm sure I'll do math with her over the summer to try to get her up to speed--any recommendations?

[....]

We use Singapore. Subtraction with Singapore is a mess in our family, too (especially in Textbook 2B). We ended up supplementing with another program last year and it cleared up a lot.

 

I think part of the problem is that we (as parents) didn't learn to subtract the way they teach in Singapore. I also think if you keep going over it, she'll eventually grasp it. There were a few concepts I had to go over and over with for the 8 yro and he finally got it.

 

Just to warn you, Book 2B subtraction is rough, too!

 

Do cuisinaire rods help at all?

[Momling]

I've found this "game" helpful. Take a number of objects (buttons, rods, pennies...), have her count them and then you cover up some in one hand. Tell her to guess how many you've got in your hand. Then of course, switch - she gets to choose a number and cover up some of them.

While playing this, you might want to write down the problem and have her write the answer. Point out the idea of "families' of addition/subtraction facts. You could show her the 10 objects in two piles of 7 and 3 and say something like "That's interesting - if I start with 10 and take away 7, I get 3. 10-7=3. And if I start with 10 and take away 3, I get 7. 10-3=7. And look, 3 + 7 is 10. And 7 + 3=10 too!"

 

Math mammoth subtraction 1, is a good, cheap supplement too.

 

Also, if you have an ipod, check out the free app "Math tappers". My youngest loves playing that. http://www.mathtappers.com/

[myfatherslily]

I recently read Ruth Beechick's book about arithmetic. She recommends that children at this age do need manipulatives and that to take them away before they're ready isn't good for their understanding of math.

 

We use Horizons, not Singapore, so I'm not familiar with the way they approach subtraction. We use cuisenaire rods every day and I think it helps. My DD is not fast. There are a lot of problems she doesn't know in her head, and those that she can figure out are usually done by counting up or down silently, not by some intuitive knowledge. But I know that by continuing to use manipulatives, she understand the "why" of it as she starts to naturally memorize.

 

We go through a set of subtraction flashcards almost every day and she uses the rods to figure out the answers. We sometimes use an abacus, but she does prefer the rods.

 

But this is my first time to teach math and I'm not good at math myself;) At this point in time, I'm just hoping that our approach will bring desired results!! lol:)

[The Governess]

I use Singapore as well. Honestly, I don't think you want to teach her tricks. IMO, you want to practice the concepts that Singapore uses until it becomes second nature to her. Then the mental process will become so quick that it will look like it is instantaneous.

 

Is she using Singapore 1B? I highly recommend purchasing the home instructor's guide and doing all the exercises on subtraction with her at home, using manipulatives and then making up some problems of your own for her to do (as outlined in the guide), using number bonds, subtracting from a 10, etc. Start with her 0-20 math facts and make sure she has them down cold, then move on from there. Use the manipulatives at each new stage until it is obvious that she no longer needs them, then switch to paper-only problems, letting her draw visual representations/cross out if needed. Eventually she will get to the place where she can quickly do the problem mentally.

 

Over the summer, you could purchase Singapore's intensive practice workbooks for 1a and 1b and go through those. I have found that they have a lot more problems that stress the number bond/making a 10 concepts that Singapore uses.

 

Singapore really is a great program, she is probably just not getting enough use of manipulatives/repetition of the procedures (do they just use the textbook and workbook? IMO it's not really enough to cement the concepts for most students) in the classroom.

[Spy Car]

I use Singapore as well. Honestly, I don't think you want to teach her tricks. IMO, you want to practice the concepts that Singapore uses until it becomes second nature to her. Then the mental process will become so quick that it will look like it is instantaneous.

 

:iagree: :iagree: :iagree:

 

There is sound logic to the variety of approaches Singapore math takes on subtraction, and good reasons for having children work those strategies repeatedly even if they seem to take longer than were they simply memorized.

 

The hard work now will pay future dividends as a facility with re-grouping numbers becomes a strong skill. Do not truncate this process if you hope to enjoy the fruits of the Singapore math approach.

 

Bill

[kchara]

I don't use Singapore, so I can't answer to that, but when my kids had problems with their addition and subtraction facts (especially my DD, who was still using her fingers at 9), I drilled. A lot. If she's getting the concept of subtraction, but just not up to par on her facts, I really, really recommend upping the drill at home. We used song CDs (constantly... during our memory work time and any time we got in the car, we had a memory work CD on, and it always had math facts on it) and timed worksheets for ours, and gave rewards when they reached a certain level on their timed worksheets. (100 problems in 5 minutes. I set another goal of 100 problems in 3 minutes, but that's something they'll have to work on on their own time, as we really need to move forward.)

[Spy Car]

IMO drill can be counter-productive to really learning the powerful re-grouping strategies programs like Singapore math are trying to teach. Doing the (admittedly) harder and slower process of working through these re-grouping strategies gives a child skills that are scaleable to ever more complex problems where "memorization" always reaches limits.

 

To drill after the re-grouping strategies have been well worked, or even in conjunction with those strategies being well worked is pretty "normal" in Singapore. But one can not neglect working the re-grouping strategies to a point of mastery or one is not going to derive the benefits of doing this stupor of mathematics education.

 

Bill

[wy_kid_wrangler04]

I would recommend you buying the Singapore books and work with her at home. Use manipulatives at home and help her that way. They are fairly inexpensive. Once you get caught up to where she is in school then I recommend you do a lesson or two ahead she she understands the concept. Any teacher that tells a young child not to use manipulatives needs to read up on child development... UGH

[stripe]

Make sure she knows addition. I think really understanding addition is essentially to comprehending subtraction. The Singapore style condensed thing, like

. . 2

. /

5 \

. .3

 

(not sure if that is formatting right, but anyway, it shows that 2+3=5, 3+2=5, 5-3=2, and 5-2=3 in one tidy diagram)

[Spy Car]

I would recommend you buying the Singapore books and work with her at home. Use manipulatives at home and help her that way. They are fairly inexpensive. Once you get caught up to where she is in school then I recommend you do a lesson or two ahead she she understands the concept. Any teacher that tells a young child not to use manipulatives needs to read up on child development... UGH

 

I think getting the books might be a very good idea.

 

I don't think the OP was saying the teacher was saying "don't use manipulatives" I believe she was saying don't "count" or use fingers, which is wise advice.

 

To the OP the Singapore method is most apparent when the value of the subtrahend in a given place exceeds the value of the minuend in that place and re-grouping is necessary. So what does that mean?

 

For sake of example, if you have 26-8 the Singapore mental math approach would be to look at 26 as 16+10. Then 8 would be subtracted from the 10 part of the (16+10) regrouping. That leaves a difference of 2+16 or 18.

 

It seems "complicated" and even slow going as the skills are built, but it is an incredibly powerful way of learning to manipulate numbers and all the work pays off!

 

You are very fortunate to be in a school that has adopted this program. Some re-education on your part may be necessary (it certainly was for me) but you may find it is actually kind of fun (and that you may be better at math than you think).

 

Bill

[The Governess]

 

Some re-education on your part may be necessary (it certainly was for me) but you may find it is actually kind of fun (and that you may be better at math than you think).

 

Bill

 

:iagree:I am definitely getting a new education. Specifically the subtracting-from-a-ten concept is really hard for me to wrap my mind around. I was taught to do the 26-8 problem mentally by first subtracting six to get to 20 and then the additional 2 to get to 18. I immediately break the numbers up this way when I see a problem like this, so I have to really think about it to do the problem the Singapore way!

 

The HIG also says you can rely on math facts. So, if you know that 16-8 is 8 then you also know that 26-8=18. This is much easier for me as well. I think at this point that my dd is better at the whole subtracting from a 10 thing than I am. :lol: I am curious to see how this concept translates into more difficult problems in higher grades. At what point does it become superior to the other mental math methods for subtraction?

[Spy Car]

:iagree:I am definitely getting a new education. Specifically the subtracting-from-a-ten concept is really hard for me to wrap my mind around. I was taught to do the 26-8 problem mentally by first subtracting six to get to 20 and then the additional 2 to get to 18. I immediately break the numbers up this way when I see a problem like this, so I have to really think about it to do the problem the Singapore way!

 

The HIG also says you can rely on math facts. So, if you know that 16-8 is 8 then you also know that 26-8=18. This is much easier for me as well. I think at this point that my dd is better at the whole subtracting from a 10 thing than I am. :lol: I am curious to see how this concept translates into more difficult problems in higher grades. At what point does it become superior to the other mental math methods for subtraction?

 

One thing I like is that (although Singapore has their standard mental math methods) that there are multiple valid mental math re-grouping strategies a child (or adult) can employ if they have a good grasp of the basic mathematics. There is no one "right way".

 

Another way Singapore teaches for approaching a problem like 26-8 is to add +2 to both the minuend and the subtrahend, so one gets 28-10=18.

 

We discussed multiple strategies (including doing the "standard algorithm" of column subtraction) when learning subtraction.

 

I would suggest to the OP to always focus on "how" your child is reasoning the answer (with her explaining the means she used to get the answer) rather than focusing on the "answer" alone. And, at times, you mY want to discuss multiple strategies.

 

Bill

[dietmom]

I think this being a new program the teachers at our school are having a hard time teaching it and I do see supplemental materials coming home that aren't Singapore materials. As a parent I really don't know how she is teaching it other than seeing the worksheets that come home for homework--but she does seem to be following the systems for regrouping and learning the mental math. But DD doesn't seem to be getting enough practice. Like I said, she can get to the right answers because she understands the concept of how to get there--but it is painstaking and she isn't using the mental math models they are teaching.

[Spy Car]

I think this being a new program the teachers at our school are having a hard time teaching it and I do see supplemental materials coming home that aren't Singapore materials. As a parent I really don't know how she is teaching it other than seeing the worksheets that come home for homework--but she does seem to be following the systems for regrouping and learning the mental math. But DD doesn't seem to be getting enough practice. Like I said, she can get to the right answers because she understands the concept of how to get there--but it is painstaking and she isn't using the mental math models they are teaching.

 

There are books called HIGs (Home Instructor Guides) for Primary Mathematics (Singapore) that you might consider getting for yourself that could help you teach at home.

 

The Standards Edition also has "Extra Practice" books (at the same level of difficulty as the Workbooks) if your daughter needs more practice. Then there are the IP books from the US Edition that amp up the challenge in an interesting way if your daughter is one who responds better to a challenge rather than more of the same. It is fine to "mix" the US IPs with the SE books (in case you were wondering).

 

There is a learning curve for teachers (both those in schools at at home) when teaching this sort of math. I think it would be smart to educate yourself so you can best help your child.

 

My son also goes to PS. They do not use Primary Mathematics at his school, but we use the program at home. It is a fantastic way to learn/teach math. I would suggest you "get your hands dirty" if you are so inclined and help your daughter really master the re-grouping strategies in Singapore. This program builds, and builds, and builds on those skills in an incremental way, and the method becomes more and more powerful. That makes it important that the foundational work is done well. Don't fall into a trap of being "answer oriented" (as in not caring how a "correct" answer is derived) but in how that result is reasoned and understood.

 

My 2 cents.

 

Bill