Monday, February 08, 2010

Letters on Playing to Learn

http://www.nytimes.com/2010/02/08/opinion/l08teach.html?ref=opinion

Two of the letter writers would like to see elementary Math education to go beyond the four operations.
"In addition, in any mathematics curriculum, including early childhood, children are capable of learning much more than the four basic operations. Where are geometry and early algebra? What about logic, measurement and estimation?"

The same letter writer as quoted above also points out the lack of social studies in Engel's ideal early schooling.

Sunday, February 07, 2010

What should a 12 year old know?

http://www.nytimes.com/2010/02/02/opinion/02engel.html?ref=opinion

Reading out loud is a terrific skill to develop!

However, by age 12, other Math concepts can be added to the four operations -- especially the middle school merry-go-round of fraction/decimal/percent.

Sunday, January 31, 2010

Division with Fractions 1 and 3/4 divided by 1/2

This is an example from Liping Ma's book:

Using Decimals
How much is 1.75 divided by .5?
1.75/.5 = 3.5


Using Fractions
1 and 3/4 divided by 1/2
1 and 3/4 = 7/4
7/4 divided by 1/2
How many half cups are in 7/4 cups?
1 half cup = 1/2
2 half cups = 2/2 = 1
3 half cups = 3/2
4 half cups = 4/2 = 2 -- this is too much

7/4 divided by 1/2
multiply 7/4 by the reciprocal of 1/2
7/4 x 2/1 = 14/4 = 7/2 = 3 and 1/2

Division with Fractions is "a topic at the summit of arithmetic". In the introduction, she asks a division with fractions question: 13/4 divided by 1/2 and offers three additional problem-solving methodologies (besides Keep, Change, Flip) -- Dividing Using Decimals, Applying the Distributive Law and You Don't Have to Multiply.

Saturday, January 30, 2010

Checking Multiplication with Casting Out Nines

Multiplication can be checked using Casting Out Nines. (rather than long division)

By studying the digits in the problem and comparing them to the digits in the answer, we can gain confidence that we have done the problem correctly.

Here are some examples:
12 x 12 = 144
The digits in 12 add up to 3 (1+2)
The digits in the other 12 add up to 3 (1+ 2)
3 x 3 = 9 (144 adds up to 9)

13 x 13 = 169
The digits in 13 add up to 4 (1+3)
The digits in the other 13 add up to 4 (1+ 3)
4 x 4 = 16 (169 adds up to 16)
We could also add up the digits in the 16 of 4 x 4 and get 7
and get 7 in the answer by casting out the 9 in the 169 so we are left with a 16 that add up to 7.

125 x 4 = 500
The digits in 125 add up to 8 (1+2+5)
The 4 is just a 4
8 x 4 = 32 and the digits in 32 add up to 5
The answer 500 also adds up to 5.

Wednesday, January 27, 2010

What You Know About Math?

Great and enthusiastic fun video about the TI-84
http://www.youtube.com/watch?v=Ooa8nHKPZ5k

Learning Math Takes Patience

Feature on an award-winning Calc teacher in North Carolina who emphasizes practice for improvement and likens the process to bettering athletic ability. The article also talks about how Math attitude affects students and performance.

Tuesday, January 26, 2010

Personal Finance Classes in High School

This is such a needed app for Math and Life!!

Economics is also terrific but can be theoretical rather than practical.

Math provides the foundation for processing and understanding personal finance and economic terms to increase savviness and savings while reducing debt.

Saturday, January 23, 2010

ACCUPLACER: College Placement Exam

The ACCUPLACER is used by many colleges for placement into Math and English.
Passing these tests is important in order to avoid non-credit remediation classes.
The title link goes to a page with a pdf of sample questions for both Math and English.

Tips for the ACCUPLACER:
http://www.collegeboard.com/student/testing/accuplacer/accuplacer-tips.html

Tuesday, January 12, 2010

Where is the GED?

While states are spending money and resources on exit exams, it would be interesting to think about using the GED as a standard. According to this document, only 60% of graduating high school seniors would pass the GED Tests on their first attempt:
http://www.acenet.edu/Content/NavigationMenu/ged/pubs/GED_Testing_Program_FactSheet_20092.pdf

GED sample questions:
http://www.acenet.edu/Content/NavigationMenu/ged/test/prep/sample_questions.htm

Wednesday, December 30, 2009

E-Newsletter Brain Teaser December 2009

Ann went from Point A to Point B.
Simultaneously Peter went from B to A.
In six hours they met and in another three hours Peter reached A.
How many hours did Ann travel from A to B?

Peter’s total travel time was 9 hours.
Assume both travel at a constant speed:
Let’s pick a speed for Peter…60 miles per hour so Peter will travel 540 miles altogether (as will Ann). He travelled 360 miles in the first 6 hours and 180 miles in the last 3 hours for a total of 540 miles.

after 6 hours, they were both much closer to A than to B


A----------------X---------------------------------B

If Ann took 6 hours to travel her 180 miles (540-360), she was only travelling 30 mph.
So it will take Ann 18 hours to travel from A to B. (540/30)

If we pick another speed, let’s say 100 mph for Peter
So he travelled 600 miles in the first 6 hours and 300 miles in the last 3 hours for a total of 900 miles.

If Ann took 6 hours to travel her 300 miles, therefore she was only travelling 50 mph.
So it will take Ann 18 hours to travel from A to B. (900/18)

Many apologies for a typo, the original problem in the e-newsletter said:
In six hours they met and in another three hours Peter reached B.

Tuesday, December 22, 2009

Monday, December 21, 2009

Wired for Math



http://www.nytimes.com/2009/12/21/health/research/21brain.html?_r=1&hp=&pagewanted=all

Brain researchers in cognitive neuroscience are finding that young children can learn Math in preschool. This changes the idea that students need to be at least 5 until their brains are ready for Math.