Comments on: How (not) to multiply http://castingoutnines.wordpress.com/2007/09/10/how-not-to-multiply/ education | teaching | math | technology Fri, 20 Nov 2009 23:57:58 +0000 http://wordpress.com/ hourly 1 By: Rosy http://castingoutnines.wordpress.com/2007/09/10/how-not-to-multiply/#comment-10563 Rosy Wed, 03 Oct 2007 09:40:51 +0000 http://castingoutnines.wordpress.com/2007/09/10/how-not-to-multiply/#comment-10563 It was really a nice video and really useful........Thanks for the info.... It was really a nice video and really useful……..Thanks for the info….

]]> By: A 7-step plan for getting a great math teaching job « Casting Out Nines http://castingoutnines.wordpress.com/2007/09/10/how-not-to-multiply/#comment-10253 A 7-step plan for getting a great math teaching job « Casting Out Nines Thu, 20 Sep 2007 14:38:52 +0000 http://castingoutnines.wordpress.com/2007/09/10/how-not-to-multiply/#comment-10253 [...] to make your own pedagogical decisions. Or you might want to stay clear of systems that use reform math pedagogy. Or embrace those systems. Whatever. Learn (through reading blogs and talking to teachers) about [...] [...] to make your own pedagogical decisions. Or you might want to stay clear of systems that use reform math pedagogy. Or embrace those systems. Whatever. Learn (through reading blogs and talking to teachers) about [...]

]]> By: TeacherJay http://castingoutnines.wordpress.com/2007/09/10/how-not-to-multiply/#comment-10051 TeacherJay Tue, 11 Sep 2007 17:20:47 +0000 http://castingoutnines.wordpress.com/2007/09/10/how-not-to-multiply/#comment-10051 The first problem here is that the Standard Algorithm she is showing is a shortcut method with no explanation... multiplication should NOT be taught that way either - at least not to start... carrying the 1 makes no sense and neither does moving in one decimal place which she did not even mention. The second algorithm she demonstrates uses the distributive property and that is usually not covered until algebra. It's a bit complicated for 4th graders. I appreciate the way that she breaks out the multiplication into 4 steps when returning to 26 x 31 because it does keep the concept of place value. We spend several years teaching place value and having kids understand that concept, the "standard algorithm" should only be used as a shortcut AFTER kids can use the longer format. The lattice method is ridiculous however. I have seen it used to work with kids that are having trouble with the methods being used in the rest of the class, and *surprise, surprise* they still have trouble and are even more confused. Before anything 2-digit by 2-digit multiplication though it would make more sense to me to teach estimation; in fact, I have discussed this before on: http://thegrandview.wordpress.com/2007/08/01/158/ The first problem here is that the Standard Algorithm she is showing is a shortcut method with no explanation… multiplication should NOT be taught that way either – at least not to start… carrying the 1 makes no sense and neither does moving in one decimal place which she did not even mention.

The second algorithm she demonstrates uses the distributive property and that is usually not covered until algebra. It’s a bit complicated for 4th graders.

I appreciate the way that she breaks out the multiplication into 4 steps when returning to 26 x 31 because it does keep the concept of place value. We spend several years teaching place value and having kids understand that concept, the “standard algorithm” should only be used as a shortcut AFTER kids can use the longer format.

The lattice method is ridiculous however. I have seen it used to work with kids that are having trouble with the methods being used in the rest of the class, and *surprise, surprise* they still have trouble and are even more confused. Before anything 2-digit by 2-digit multiplication though it would make more sense to me to teach estimation; in fact, I have discussed this before on: http://thegrandview.wordpress.com/2007/08/01/158/

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