Comments on: How to multiply binomials using a box!

By: Rebecca Zook

Rebecca Zook — Mon, 05 Dec 2011 20:47:41 +0000

Kari, thanks so much for your superthoughtful comment! Wow, I totally neglected to mention area in the video, and you’re right, it needs to be in there! I will definitely incorporate your feedback into future versions. Thanks for your comment, and it’s nice to “meet” you here!

By: Kari

Kari — Mon, 05 Dec 2011 20:43:09 +0000

Rebecca – I’m so relieved to see that you are presenting other ways of understanding the distributive property than the FOIL method, which does not work well for multiplying polynomials with more than 2 terms. Unfortunately, the box method becomes nothing more than a magic trick (much like the FOIL method) if it is presented without associating it with area. The only reason that we know that the left side of the equation is actually equal to the right side is because they are both respresentations of the AREA of the SAME box.

For example: (x+2)(x-7)=x^2-7x+2x-14 BECAUSE
if I label the width of the box as x+2 and the length of the box with x-7 then one way to express the area of the box is
Area=length*width=(x+2)(x-7). I can also calculate the area of the larger box by finding the area of each of the smaller boxes and adding them up. This gives me the expression on the right side of the equation above. We can only conclude that these two expressions are EQUAL because they represent the area of the same box. Without that critical piece of information, there’s no good reason that these two expressions SHOULD be equal.
(PS I teach math everyday at a community college in Oregon – good job overall

By: Rebecca Zook

Rebecca Zook — Wed, 30 Mar 2011 01:25:38 +0000

You are soooooooooo welcome!!!

By: Taylor B.

Taylor B. — Wed, 30 Mar 2011 00:59:49 +0000

Thank you so much for showing me another alternative to foiling! Thease videos are wonderful. I appreciate you for helping me understand better. You explain math so well.

By: Rebecca Zook

Rebecca Zook — Mon, 19 Jul 2010 02:31:20 +0000

April, it’s so nice to “meet” you! Thanks for stopping by. I’m really excited to share this idea because I think it’s an easier way for some people to learn how to multiply binomials. Thanks for sharing your blog post, too!

By: April S.

April S. — Mon, 12 Jul 2010 19:34:10 +0000

These videos are great! I’m so glad to see an alternative to FOIL as it is a limited use concept. You’ve explained things so well and I love the visual style.

Wish I had seen this before I blogged about our FOIL video.
http://blog.thinkwell.com/2010/07/prealgebra-multiplying-binomials.html