Homeschool Math Newsletter, Vol. 34, November 2009
The American Math Challenge
- Free registration and participation with great prizes to be won -
Students aged 9-14 from across America are invited to battle it out in an
exciting online math challenge, competing live, in a safe, multiplayer
game environment.
Students will answer as many correct questions as they can in 60-second mental arithmetic challenges live, against other students as well as national curriculum problem solving questions at their own
pace. Register free!
Week 1: Nov. 2-8 is Practice week
Week 2: Nov. 9-16 is the American Math Challenge
Hurry, register today! www.americanmathchallenge.com
In this month's newsletter:
1. Percentages with mental math
2. Converting between metric and U.S. measuring systems
3. Math Apprentice
4. Tidbits
1. Percentages with mental math
In this article I want to explore some ideas for using MENTAL math in calculating percents or percentages.
I have made this video of percent & mental math strategies as well:
And here are the ideas:
- Find 10% of some example numbers (by dividing by 10).
- Find 1% of some example numbers (by dividing by 100).
- Find 20%, 30%, 40% etc. of these numbers.
FIRST find 10% of the number, then multiply by 2, 3, 4, etc.
For example, find 20% of 18. Find 40% of $44. Find 80% of 120.
I know you can teach the student to go 0.2 × 18, 0.4 × 0.44, and 0.8 × 120 - however when using mental math, the above method seems to me to be more natural.
Read #4 - #9 of the mental math ideas here.
2. 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!
Read the rest of them on my blog!
3. Math Apprentice
Math Apprentice is a new free website, meant to show students how math is used in real world. In the game, you are like an apprentice at various companies, applying your math skills to challenges similar to those encountered in the real world and real companies.
To begin, you click the button on the home page of the site that says "Explore the Math". Then choose your character, and you'll be on the main street (see screenshot above) . Then use arrow keys to move right or left, and click to select a company to visit.
The companies you can visit are:
- Sweet Treat Cafe - baking pies
- Wheelworks - constructing bicycles and exploring gear ratios
- Game Pro! - keep track of the distance between superhero and the villain in a computer game, using Pythagorean Theorem
- Spacelogic - study speed of a spacecraft & slope, and then angle & distance commands to get the space rover where it needs go.
- Trigon Studios - Explore the usage of sine and cosine functions to create rhytmic or repeating motion of animated objects.
- Doodles - explore polar curves created with sine and cosine. These can be like stars, flowers, or spirals.
- Builders, Inc. - calculate areas and perimeters of shapes
- Adventure Rides - study the angle of elevation and height of a roller coaster
Read the rest of my review and see screenshots.
4. Tidbits
- Cell size and scale
Zoom in to see various things starting from a coffee bean and down to a skin cell, human egg, red blood cell, bacteria, viruses, hemoglobin, glucose and molecules, etc., all the way "down" to a carbon atom. In a measuring scale, you go from millimeters (0.001 or 10-3m) to micrometers (0.000001 or 10-6m) to nanometers (0.000000001 or 10-9m) to picometers (0.000000000001 or 10-12m).
- Algebra: the problem is in the translation
This is a post by Denise at Let's Play Math. She explores, through and example problem, how to translate the words of a problem into a mathematical calculation or algebraic equation. If this area gives you trouble, her blogpost is a must.
- Discovery Education's Puzzle Maker
A free puzzle generation tool for teachers, students, and parents. Create and print customized word search, criss-cross, math squares, number blocks, mazes, letter tiles, and more.
- NAEP math test results are in
The National Assessment of Educational Progress (NAEP) math tests given early in 2009 show that the US fourth graders scored the same as in 2007, and 8th graders gained a little over 2007 tests. This is commonly called "the nation's report card". I guess it shows things haven't changed since 2007 in the realm of math education; however the test results are better now than when they first started administering the test in 1990's.
- The American Math Challenge
This is a free math contest coming up soon in November where students aged 9-14 from across America are invited to battle it out LIVE against other students using 60-second arithmetic challenges and also other math questions. See also the advert at the top of my newsletter.
Till December,
Maria Miller
Miss something from the earlier volumes? See newsletter archives.
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