# Talk

## gelosia multiplication

(22 Posts)
RedHelenB Thu 17-Mar-16 10:40:31

Just realised that this seems the favoured method for y10s I have come across. Have you taught your child the old fashioned method as it seems to me to be quicker?

noblegiraffe Thu 17-Mar-16 10:51:19

From experience (maths teacher) kids are more likely to get the right answer more quickly with a lattice than the column method. The most common mistake when using the column method is to forget to add zeros when multiplying by tens, hundreds etc. Because of this I advise against columns.

Grids are the most likely to be used IME. Bloody hate the grid method, the addition at the end is ridiculous.

2016IsANewYearforMe Thu 17-Mar-16 11:08:11

Are you talking about 10 year olds, or year 10s?

RedHelenB Thu 17-Mar-16 12:39:11

year 10s.

2016IsANewYearforMe Thu 17-Mar-16 15:41:02

That seems really odd to me. I would have thought that 15 year olds would be able to do compound multiplication the "old fashioned" way.

Your post reminds me of a recent article on the BBC about the furore in the USA over common core.

www.bbc.co.uk/news/blogs-trending-35788369?SThisFB

Quote from educational expert at very end of article.
"The way kids learn and the way mathematics has been classically taught - and is taught in the high achieving countries - is that students learn one method."

noblegiraffe Thu 17-Mar-16 19:35:14

Why is the 'old fashioned way' any more virtuous than the lattice method?

disquit2 Thu 17-Mar-16 19:41:35

Why is the 'old fashioned way' any more virtuous than the lattice method?

The old fashioned method is preferable in the context of higher level and multi-step mathematics, not least because it is faster. I find a bit ludicrous that UK maths undergraduates come in using other slower methods (especially the grid method) and then we have to teach them something they should have been taught in primary school.

disquit2 Thu 17-Mar-16 19:43:19

BTW the private selective schools around me do teach the column method and encourage its use. Kids coming in from state schools are taught not to use grids. But these are high ability students.

noblegiraffe Thu 17-Mar-16 19:51:32

Grid method is definitely slower than column but I'm not convinced that the lattice is. Kids are more likely to get the right answer with it too.

I think some people just see the column as better because that's what they did at school and the lattice confuses them.

disquit2 Thu 17-Mar-16 20:59:59

I think some people just see the column as better because that's what they did at school and the lattice confuses them.

This may well be true of some people, but probably not of those who work in science and engineering and who prefer students to use column methods.

My main complaint is that lattice is slower, as it involves more immediate steps to be written down. The latter may well improve accuracy for children, but is less helpful for more advanced students for whom speed in basic operations is of the essence. In addition lattice seems to obscure understanding of place value and approximations: we observe correlations between weaknesses in the latter and use of lattice over column.

noblegiraffe Thu 17-Mar-16 21:10:51

If speed is of the essence and the calculation requires a column or lattice, then why the bloody hell aren't you using calculators?

I still don't think the lattice is slower. I use it personally because it's faster and easier, and I'm a maths teacher who is certainly capable of using columns.

If you want a method that really teaches understanding of place value, then that's the grid.

Incidentally, I'm sure that you are aware that correlation does not equal causation.

2016IsANewYearforMe Thu 17-Mar-16 22:41:43

I find the column method to be more efficient. Once you understand the concept, and by 15 years old you really should, the point is to be as quick and accurate as possible. Of course a calculator would be even quicker, but many exams and tests don't allow calculators. And to answer the questions, you often need to multiply competently as an intermediate step. So, for me, it's in a child's best interest to be comfortable with the column method.

noblegiraffe Fri 18-Mar-16 08:40:26

Having mastered both, I have switched to a lattice as faster and more accurate, and from teaching thousands of kids, I find they are more likely to get the correct answer with a lattice.

senua Fri 18-Mar-16 08:49:38

This lattice/gelosia thing is news to me. It seems quite neat but how can it be faster ?
The (a) writing out of the sum, (b) writing out the result of the multiplications and (c) adding together of the columns/diagonals is common to both methods, but the lattice involves having to draw out the boxes and diagonal lines so surely that adds to the time taken?

The old Numeracy strategy used the grid method as a stepping stone to the standard column method. It is useful as it reinforces the place value of the digits in the sum. But ultimately the column method is the goal.

The new primary curriculum from year 3 certainly pushes the column method where children are taught to jump through hoops without really understanding what they are doing

DelphiniumBlue Fri 18-Mar-16 09:30:09

Can someone explain the lattice method? Have never come across that term. Thanks

2016IsANewYearforMe Fri 18-Mar-16 10:01:58

Here is a link to the lattice/gelusia method for multiplying:

en.wikipedia.org/wiki/Lattice_multiplication

irvine101 Fri 18-Mar-16 10:27:26

My ds uses both lattice and column, depend on how he is feeling. But lattice always gives correct answer and he is likely to make silly mistakes using column. I wasn't sure that children are allowed to use lattice at secondary school, so I was encouraging him to use column more. But is it safe to assume you are allowed?

noblegiraffe Fri 18-Mar-16 10:51:07

Lattice is no longer allowed at KS2, they will have to use column for this May's SATs, BUT any method for multiplication is allowed in the new GCSE - this is confirmed.

I don't know whether this will change in the future, but for now secondary students can safely use lattices or grids.

noblegiraffe Fri 18-Mar-16 10:55:46

how can it be faster?

I find it faster because when you are doing the multiplication you are only doing the basic times tables, you don't need to worry about carrying or adding what you carried. The adding and carrying only comes at the end, where with the column you are adding and carrying as you go along and at the end.

Once you've got the hang of drawing the grids they take hardly any time to draw, so long as you do it by hand and not with a ruler.

irvine101 Fri 18-Mar-16 14:47:20

Thank you noble.
And I agree, he is actually faster with lattice.

RafaIsTheKingOfClay Sun 20-Mar-16 07:41:25

The most common mistake when using the column method is to forget to add zeros when multiplying by tens, hundreds etc

Interestingly, this would lose you the method mark in the ks2 paper, giving you 0/2. I suspect for many children it would be better to teach a lattice method, that they get right almost all the time, as the correct answer will get 2 marks regardless of the method used to get there.

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