10/10 and the Metric Week

Photo courtesy of Miss Colleen

Today is 10th of October or 10/10. As we know, the metric system is based on number 10. Thus, the week ending today has been designated as the metric week..

The National Council of Teachers of Mathematics (NCTM) started the National Metric Week tradition in 1976. Please read a little bit more about the history of the Metric Week here.

You could celebrate the Metric Week doing some metric units puzzles and quizzes. Here's a link to postal stamps and cards celebrating the metric system.

NCTM has tons of related resources so I'll mainly point you there.

I grew up using the metric system, and so I've actually had to learn the imperial system while authoring math materials. These days, it seems, I know the U.S. system better than the people around me... But the metric is sure easier, as far as calculations and conversions go, since you just have to remember it goes by 10s.

In fact, to fully operate in this world, it seems it's best to know both.

Converting between metric and U.S. measuring systems

Here are a few helpful guidelines if you find yourself having to switch between one or the other. I have these conversion factors memorized from much of use. Not that everyone else would actually use these all as much as I do, being in the business of authoring math materials, but anyway:

1 quart ≈ 1 liter, but 1 quart is slightly less.
1 liquid ounce ≈ 30 ml. From this, one can figure out that 1 cup ≈ 240 ml and 4 C ≈ 960 ml.

1 inch = 2.54 cm
It's an awkward number but I need to use this conversion factor constantly, when working with images on my computer, which has a resolution of 96 pixels per inch... but I need the image to print out as 5 cm long or whatever.
You could use 1 inch ≈ 2.5 cm.

Another way is to think about those typical student rulers which are 12 inches = 30 cm. So... 4 inches is 10 cm.

Also... 1 inch might very well be the length of your thumb's last bone (the bone that contains the nail). Check! And 1 cm might very well be the width of any of the other fingernails. Check!

1 yard ≈ 1 meter; better yet 1 yard ≈ 90 cm and 1 meter = 100 cm. You see, that student ruler was 12 inches = 1 foot ≈ 30 cm.

1 mile ≈ 1.6 km. Or, 5,000 meters or 5 K is a popular running distance... about 3 miles.

1 pound is about 450 g, but actually it's easier to remember 1 kg = 2.2 lb.

It's fairly easy to multiply by 2.2. I have a metric scale; I might weigh about 55 kg. 55 x 2 = 110 and 55 x 0.2 = 11. So I weigh about 121 lb.

And 1 ounce ≈ 30 g. Just like 1 liquid ounce was about 30 ml.

To convert anything, go to Google and type

25 lb to kg
8 m to inches
22 km to miles
etc.

Math contest for homeschoolers (elementary)

Noetic Learning is holding a math contest for elementary students that homeschoolers can take part in. Here are some details about this contest:

• Registration deadline: October 18,2009 (coming up soon!)
  
• Contest Date: October 26-30 2009
• Who: any students (grades 2 - 5)
• Location: your home
  
• Fee: $8 per student per contest

My daughter is taking part. We will see how it goes. The purpose of a math contest is definitely NOT to discourage a child or to put additional burden on him. I'm basically checking to see if this contest can be a means of inspiration and motivation for my daughter.

www.noetic-learning.com/mathcontest/homeschool.jsp

Spread of H1N1 (swine) flu and mathematics

I came across an interesting blog post by Murray Borne titled H1N1 and the Logistic Equation. It explains how a logistic function can be used to model the spread of a virus or a disease in a given population.

Now, maybe you don't know what is logistic function or equation. It is shown in the blogpost; it uses the exponential function as a part of it. Basically, it is like an exponential growth function but it is limited after a certain point so that the growth tapers off, and approaches a certain (upper) limit.

Murray shows the graph, and then shows a real-life example about the spread of swine flu in Mexico last spring. It's a great, yet fairly simple, example of how mathematics is used for modeling real-life situations.

You could definitely use it as such an example with your students, even if you don't understand a THING about logistic equations. You see, seeing how math is used is definitely inspiring and motivating to a lot of students - especially when it ties in with some current "hot topic" such as the H1N1 flu.