Saturday, November 29, 2014

What happened?

Whenever I travel I try to take as many photos as I can that are worthwhile but not find-able all over the web. No sense taking pictures that have already been taken. I look for unique pictures. Even more so, I like them to be though-provoking.

This one I took while walking on a dock in St. Thomas, USVI, a bit over a year ago. I can tell you that the hat was floating, although some people to whom I have shown the picture thought I had caught it in midair. That led me to consider how we describe what we see, and how we extrapolate in the process.

Anyone who describes the hat as in midair must presume some person, or some thing, as the thrower, unless perhaps it was windblown.  Even knowing it is floating, the question could still be asked: How did it get there?

So, if I was to ask you to write the history of this hat, as best you can, how would you respond?

Friday, November 21, 2014

FOILed again?

The statement in red here is one I came across while taking another look at Common Core standards. I decided to Google the statement. I did discover that Google will not let you use more than 32 words between quotes, so I Googled just the 1st sentence in quotes (so Google looks for an exact match), and got 14,100 hits. Listed below are just a few of them.

There is a world of difference between a student who can summon a mnemonic device to expand a product such as (a + b)(x + y) and a student who can explain where the mnemonic comes from. The student who can explain the rule understands the mathematics, and may have a better chance to succeed at a less familiar task such as expanding (a + b + c)(x + y).

It's a bit misleading. The second sentence says "may have a better chance". Anyone who really and truly understands what binomial multiplication is and why it is, WILL have a better chance. A much much better chance.

It's also interesting that the statements refer to "a mnemonic device" and gives it a bad flavor. I suspect the device the authors had in mind was the old FOIL method for binomial multiplication, and the impetus behind the statements was the knowledge that there are teachers who taught only FOIL, and nothing more. (Could it be in use here only because F-O-I-L actually spells a word in English? Could this be why US math is falling behind?!? Imagine!?!) Do you know the meaning of FACE? Does it help or hinder in music studies?

I find it odd that a statement which embodies such a major thrust in educational philosophy is phrased in the context of binomial multiplication.  Multiplying binomials is something most people never do in their lives. However, if binomial (and polynomial) multiplication where actually dealt with carefully and fully they would be recognized as the foundation behind most algorithms for multiplication. Multiplying a pair of two digit numbers is actually a binomial multiplication. Multiplying 564 and 37 is actually multiplying a trinomial and a binomial. (I find it interesting that my spell-checker just marked "trinomial" as a misspelled word. For the record, it does not acknowledge "pf" as a possible error.)

The 4th grade standards include this: Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.

The arrays and area models referred to here are exactly the same devices that are, or could be, used to describe the distributive process applied when multiplying polynomials. It would be nice if our educational system would recognize this and capitalize this, and perhaps gather 4th grade and high school teachers together to carefully comb out more connections. I an willing to bet that a substantial number of 4th grade teachers are not tuned in to the distributive rule as it relates to polynomial multiplication. A few visuals are here.

Whatever happens with Common Core, let's at least recognize that it doesn't have all the right answers, but it could be spurring people into asking the right questions. I hope.

Thursday, November 6, 2014

GeoGebra no later than middle school...

This is just a continuing saga of options that teachers and students now have that I hope they are using.  with the technology we have now students can be introduced to new things in dynamic ways making them accessible as never before.

I just made this in GeoGebra as an example of check boxes in case I needed one at the AMTNYS conference presentation next week.

Wednesday, November 5, 2014

A Heart for Mathematics

Basic geometry as work. Circles with radii 1, 3, and 6, centered at the origin and 3 units below. Two points rotating counterclockwise at the same rotational speed, one clockwise at twice that speed. Those points are connected to form a triangle, and two angle bisectors shown. The trace shows the path of the point of intersection of those medians, the incenter.

There is a lot of mathematics in this diagram. I believe that creations such as these can be used with young students to "hook" them into mathematics long before they know the math needed to write equations for such graphs. Although the equation would be heavy into trig, the creation of the graph requires no trig at all. Basic geometric concepts such as circle, line, bisection, rotation are just about all that is needed. 

A tremendous amount of mathematics can be learned by setting kids loose with GeoGebra and a basic knowledge of the GeoGebra toolbar. In many respects, kids would probably learn GeoGebra faster than adults.

Animations and GeoGebra will be the topic of my session at the AMTNYS (Association of Mathematics Teachers of New York State) annual conference in Syracuse next Monday.