FOIL method. Good or bad?

Jomo

Elite Member
Joined
Dec 30, 2014
Messages
10,718
Can someone explain to me the benefit of learning the FOIL method, if any?
The FOIL method is restrictive to just multiplying two factors that each has two terms. Students still need to learn how to multiply factors that don't have two terms each. Since this last procedure also includes how to multiply two factors each with two terms, then I feel that teachers are showing an extra rule when they show the FOIL method.

Having students learn an extra rule when not needed is not beneficial to the students. They have enough to learn!
 

pka

Elite Member
Joined
Jan 29, 2005
Messages
11,140
FOIL is great for outdoor cooking. In mathematics it has no place.
 

Dr.Peterson

Elite Member
Joined
Nov 12, 2017
Messages
11,798
Since my students typically have already learned FOIL (or at least recall the name), I have to mention it; but I do so after teaching the full method, which I just call "each by each" (which is surely at least as memorable, and easier to carry out). Then I just point out that FOIL is nothing more than a way to describe the results that we got more easily, which happen to be in exactly the same order.

But I'd be quite happy if no one taught it. And I refuse to ever use it as a verb.

Well, it does have one advantage: Sometimes I need to remind a student I didn't teach, that they need to distribute, and if I just say, "Remember FOIL?" they usually know what I mean. Somehow, "Just distribute" or "Expand" isn't as familiar to them.
 

lookagain

Elite Member
Joined
Aug 22, 2010
Messages
2,805
Foil is used for indoor or outdoor cooking. F.O.I.L. I recommend each day for the rest of my life
and the students' lives and the whole mathematical community, necessarily taken together with
the teaching of multiplying of two or more general polynomials. F.O.I.L. is another handy
mnemonic/tool, and it can help ease into the multiplication of different polynomials. You don't
have to see this as a competition of methods. I see them complementing each other. It's good.
 

Harry_the_cat

Elite Member
Joined
Mar 16, 2016
Messages
2,625
I always have taught the F.O.I.L method for expanding. I find it useful to refer back to when teaching students how to factorise trinomials - how and why you have to turn the middle term into two terms. Then I go on to the quicker method for factorising, what I call the cross method.
 

Otis

Elite Member
Joined
Apr 22, 2015
Messages
3,031
Can someone explain to me the benefit of learning the FOIL method, if any? … Having students learn an extra rule when not needed is not beneficial to the students …
'FOIL' is a memory device, Jomo. One benefit is: giving beginning students a way to recall/identify the four multiplications needed, when using double distribution to write the product of two binomials.

😎
 

Jomo

Elite Member
Joined
Dec 30, 2014
Messages
10,718
'FOIL' is a memory device, Jomo. One benefit is: giving beginning students a way to recall/identify the four multiplications needed, when using double distribution to write the product of two binomials.

😎
I like your answer. I need to give this some thought.
 
Top