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Grid Method for multiplication - are your pupils weaned off it by end of year five?

Discussion in 'Mathematics' started by mounthood, Sep 10, 2011.

  1. I am a secondary teacher and when I first came across grid method I was impressed but that only lasted a couple of years because you find that with the bigger numbers the kids get lost amongst all those numbers they have to add up at the end. I see its value in junior schools only because it is easy to teach and that is the only reason. I personally prefer the so called Chinese method, the one with the grid with the diagonals added. If you know it it is the one where the highest calculation you ever have to do is 9 x 9, then the answer just falls out at the end almost like magic. You can do any multiplication calculations and it is impressive. Of course it is a little harder to teach initially. One of the problems with basic maths skills is that the methods you were taught first are the ones you understand and tend to stick with for the rest of your life. Although I like the Chinese method I still use long multiplication generally, or rather a calculator to be honest. And don't get me onto division, cos we all use calculators for that one anyway. Multiplecation skills work nicely and are good to learn, division is just a pain in the butt!
     
  2. Anonymous

    Anonymous New commenter

    I couldn't really care about the need for the average student to multiply 3 digits by 2 digits. They can have a method but when was the last time the average student needed it in real life -most people would use a calculator.
    What I do care about is students who don't seem to MENTALLY be able to do a calculation like 38 x 6 for example.
    Even bright students I tutor who can do fancy algebra sometimes struggle to quickly do this kind of calculation.
    And don't get me started on mental division.
     
  3. Anonymous

    Anonymous New commenter

    Or can't even approximate the answer to 38 * 6.

     
  4. Great topic all,
    I agree on two points,
    firstly as a teacher it is your job to teach students at their level not to blame previous teachers.
    secondly as a primary teacher the maths requirements always baffle me. Is it all right to excuse the lack of teaching long multiplication because it gives better grade scores, please this just shows the way in which education is going to the toilet.
    Did anyone become a teacher to pass grade scores.
    I think that the best way to teach maths is to try and show your students all the strategies and they can pick the one they like the best. To say that they get confused in primary is a bit misleading, as surely the reasons behind the strategy should be explained to them.
    Also to say that they are going to use calculators is buck passing to.
    Is the real problem not that the teaching c curriculum should focus in producing a good math brain in every student rather than one that can pass a basic test.
    Oh well I tried.
     
  5. PaulDG

    PaulDG Occasional commenter

    As you may tell from my contributions to this thread, I blow two ways on this one.

    For limited situations, I quite like grid - it's consistent when used with algebra, and it does actually show what's going on.

    But I do not believe it "scales".

    When the number of digits involved in a calculation increase, it soon becomes unwieldy and also the errors climb as transcription of all the zeros becomes a big problem

    So why teach it if it does not scale? Why not go for long multiplication?

    Well, reality is, with the reduced practice that is now encouraged by modern box-ticking teaching, they can get the sort of small questions they're going to be asked in GCSE right with grid and grid requires less practice to be just about OK at.

    And in the real world, they'll be using calculators... So why should they "waste" (or "invest") time in practising long multiplication? When will they ever use it?
     
  6. DeborahCarol

    DeborahCarol New commenter

    Sorry, but, as a tutor of secondary students, I can tell you that this strategy has proved disastrous.
    I see Year 9/10 students with quite good maths ability who have been handicapped by their not having had sufficient practice at ONE, EFFICIENT, written method for addition, subtraction, multiplication and division - method that 20 years ago would have been under their belt by Years 4/5.

     
  7. DeborahCarol

    DeborahCarol New commenter

    About ten years ago, we stayed at a cottage in Brittany. Landlord was calculating how much electricity we'd used. In her 30s max, she wrote out a long division (very quickly) with decimal remainder. She didn't need a calculator because she'd been taught arithmetic.
    In the 'real world', (most) people don't solve equations. But of course equations can be solved with (certain) calculators. Does that mean we shouldn't teach algebra?
    In the 'real world', most people don't write stories. Does that mean we shouldn't teach creative writing?
    In the 'real world' some people do actually do long multiplication! I have, many times, and I don't believe it's just because I teach maths (primary-trained). The people who don't are often those who didn't have sufficient practice at school - probably because they had teachers who didn't think long mult and long div were important because 'in the real world they'll have calculators'.
    Isn't it our job to teach children maths?

     
  8. Doitforfree

    Doitforfree Star commenter

    I don't carry a calculator round with me, but I usually have my brain on board, and it's a lot quicker than a calculator almost every time, for the sort of every day problems like which toliet roll is cheapest (oh yes, I'm the one gazing at all the prices while I work out which one is really the best value, taking into account number of sheets per roll, any freebies and my own variable for, shall we say, quality of tissue).
     
  9. Karvol

    Karvol Occasional commenter

    I believe the phrase is "too much information".

     
  10. DM

    DM New commenter

    Perhaps flatulent Doitforfree is three sheets to the wind?
     
  11. Doitforfree

    Doitforfree Star commenter

  12. I'm a secondary maths teacher and I teach both methods. The grid method is better for showing exactly what your doing. With my very low ability year 11 last year I encouraged them to use the grid method as even though there are more places to go wrong they would get marks for correct answers in the grid. I suspect that they would never need to do a long multiplication without a calculator after they left. If students can't multiply decimals using the grid method (multiply by 10 etc to make whole numbers, then divide by the same numbers after you've got the final answer) then they won't be able to use traditional long multiplication. Grid method is also useful for multiplying brackets in algebra. I have found that pupils educated in Pakistan use the older method, but put a cross where I would have been taught to put a 0.
     
  13. I have a set 2 out of 4 year 7 class. Before I taught them they were asked to calculate 37 x 78 They were given as long as they wanted. and encouraged to use whichever mehod they wanted. None of the 30 students used the grid method. Alarmingly, with most of them using variations on the tradiional approach there was only 1 pupil who got he correct answer. I decide that I had better give them an easier question before I showed them how to do it. The question 24 x 6 resulted in 6 correct answers out of the 30 students. None of these showed any method and appeared to have done it using mental methods. When I demonstrated the grid method 10 said they remembered seeing it at some time.I'm sorry if I offend our Primary colleagues but I find it unacceptable that 67% of pupls who are level 4 (or even level 5) according to KS2 Teacher Assessments cannot do a double digit single digit multiplication.
     
  14. Maths_Mike

    Maths_Mike New commenter

    I totally agree but (sadly) am not surprised - many of them probably dont even know their tables which means there pretty much stuffed regardless of any methods they may know!
     
  15. DM

    DM New commenter

    Fixed that for you.
     
  16. Maths_Mike

    Maths_Mike New commenter

    OOPS - you missed that!
     
  17. Anonymous

    Anonymous New commenter

    Well it's a good thing most 16 year olds know their tables then, isn't it?
     
  18. DM

    DM New commenter

    Eh?
     
  19. DM

    DM New commenter

    No I didn't! I'm too busy with avatar duty to attend to your written English Mike!
     
  20. To check on whether they knew their tables I got them to do 10 Quick Questions twice. Once at 10 seconds per question and once at 5 seconds per question. These were times tables questions which, as it turned out, just tested tables up to 11 X. Virtually all got 10 out of 10 on 10 seconds per question and most got about 8 out of 10 on 5 seconds per question. This suggests that they know their tables reasonably well so the reason for getting the double digit multiplcations wrong must be that they haven't mastered the technique.
     

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