Minggu, 30 Desember 2007

Word problems in Russia and in America

Recently I had the opportunity (HT Let's Play Math) to read an article "Word Problems in Russia and America" by Andrei Toom. It is an extended version of a talk at the Meeting of the Swedish Mathematical Society in June, 2005.

It made for quite interesting reading.

The article was comparing word problems in Russian and U.S. math books. As you can guess, the former were far more advanced than the latter.

I want to highlight a few things from the article. You're very welcome to download and read it too from the above link.

A problem from a Russian fourth grade book:
An ancient artist drew scenes of hunting on the walls of a cave, including 43 figures of animals and people. There were 17 more figures of animals than people. How many figures of people did the artist draw?

A similar problem is included in the 5th grade Singapore textbook:
Raju and Samy shared $410 between them. Raju received $100 more than Samy. How much money did Samy receive?

Now, these are not anything spectacular. You can solve them for example by taking away the difference of 17 or $100 from the total, and then dividing the remaining amount evenly:

$410 − $100 = $310, and then divide $310 evenly to Raju and Samy, which gives $155 to each. Give Raju the $100. So Samy had $155 and Raju had $255.

A far as the figures, 43 − 17 = 26, and then divide that evenly: 13 and 13. So 13 people and 30 animal figures.

BUT in the U.S., these kind of problems are generally introduced in Algebra 1 - ninth grade, AND they are only solved using algebraic means.

I remember being aghast of a word problem in a modern U.S. algebra textbook:

"Find two consecutive numbers whose product is 42."

Third-grade kids should know multiplication well enough to quickly find that 6 and 7 fit the problem! Why use a "backhoe" (algebra) for a problem you can solve using a "small spade" (simple multiplication)!

I know some will argue and say, "Its purpose is to learn to set up an equation." But for that purpose I would use some some more difficult number and not 42. Doesn't using such simple problems in algebra books just encourage students to forget common sense and simple arithmetic?

(BTW, no matter what number you'd use − "Find two consecutive numbers whose product is 13,806" − I'd just take the square root and find the neighboring integers, and check.)

And this is what Toom also wonders greatly: why do U.S. instructors not teach children to solve many-step word problems using arithmetic only? It is as if the more complex word problems are extinct in the standard textbooks until algebra, and word problems in elementary grades are mostly reduced to one or two-step simple problems.

(I've written about that before, how the word problems found in lesson X are always solved using the operation taught in lesson X.)

Another example, a 3rd grade problem from Russia:

A boy and a girl collected 24 nuts. The boy collected two times as many nuts as the girl. How many did each collect?

You could draw a boy and a girl, and draw two pockets for the boy, and one pocket for the girl. This visual representation easily solves the problem.

Here's an example of a Russian problem for grades 6-8:
An ancient problem. A flying goose met a flock of geese in the air and said: "Hello, hundred geese!" The leader of the flock answered to him: "There is not a hundred of us. If there were as many of us as there are and as many more and half many more and quarter as many more and you, goose, also flied with us, then there would be hundred of us." How many geese were there in the flock?

(I personally would tend to set up an equation for this one but it can be done without algebra too.)

Toom talks about how "real life" word problems are emphasized in America, and "fantastic" problems that could not occur in reality are devalued. For example, a problem such as
"Sally is five years older than her brother Bill. Four years from now, she will
be twice as old as Bill will be then. How old is Sally now?
" may be deemed unfit since nobody would want to know such in real life.

However, like Toom argues, such problems do serve a purpose: that of developing children's logical and abstract thinking and mental discipline. One-step word problems won't do that!

In the U.S. word problems are perceived as "scary"; both students AND teachers tend to be afraid of them, and teachers might even omit solving them. This doesn't help, of course.

Here's a joke that Toom had included in his article, by Lynn Nordstrom:

"Student's Misguide to Problem Solving":

  • Rule 1: If at all possible, avoid reading the problem.Reading the problem only consumes time and causes confusion.
  • Rule 2: Extract the numbers from the problem in the order they appear. Be on the watch for numbers written in words.
  • Rule 3: If rule 2 yields three or more numbers, the best bet is adding them together.
  • Rule 4: If there are only 2 numbers which are approximately the same size, then subtraction should give the best results.
  • Rule 5: If there are only two numbers and one is much smaller than the other, then divide if it goes evenly -- otherwise multiply.
  • Rule 6: If the problem seems like it calls for a formula, pick a formula that has enough letters to use all the numbers given in the problem.
  • Rule 7: If the rules 1-6 don't seem to work, make one last desperate attempt. Take the set of numbers found by rule 2 and perform about two pages of random operations using these numbers. You should circle about five or six answers on each page just in case one of them happens to be the answer. You might get some partial credit for trying hard.


I hope your students do not fit the above joke.

In my books, I've tried to avoid problems that would lead children to the above scenario. I do not claim to be perfect in this; I feel I have lots to learn. But I will keep striving to make problems that do require many steps and that do not "dumb down" our children, but that progressively get more difficult as school years go by.

See also what I've written in the past concerning word problems.

Rabu, 26 Desember 2007

Some good math blogs

I was surprised to find that Denise had included me in her Math Bloggers Hall of Fame. Thanks! I feel honored to be a part...

On her list, I found some new reading material from the other blogs listed. Found some interesting posts right off the bat:

Snowflake math - this is a neat lesson plan. Makes kids thing spatially.

Teaching: The Really Big Number (applied). This is a lesson plan about the problem where you need to find the remainder of 100100.

Both of these are obviously from good teachers. Enjoy.

Selasa, 18 Desember 2007

New Math Mammoth books

As the year is approaching its end, and a new one is around the corner, so are some new Math Mammoth books and other news.

Some new ones are already here, from the Green Series. These are collections of worksheets especially good for teachers who need worksheets on a certain topic or topics but with somewhat varying difficulty. They work good for a review, too:
Also, Math Mammoth Money book has gotten a "sister" version with Canadian coins: Canadian Money.

The news some of you might be interested in is that my Lightblue Series complete curriculum books for grades 1, 2, and 3 will be available as downloads from the beginning of 2008, at Kagi store. The price will be $27 per grade level.

And, the fourth grade material for the Lightblue is coming along, as well. I hope to have it ready in February-March. Also in January I will publish two new books titled Math Mammoth Multiplication 2 and Math Mammoth Division 2. These two will replace the current Multiplication & Division 2 book, and will have better (and very fresh!) material.

Senin, 10 Desember 2007

The 12 contests / the 12 blogs of Christmas

I admit; I think the folks at HomeschoolEstore have come up with a really creative promotion!

They've invited 12 bloggers to host 12 different contests on their blogs, and each winner will get a $50 gift to spend at HomeschoolEstore.

Now, I'm not one of those blogs... In fact I can't even participate in any of the contests since I'm a publisher (my products are sold there). But I do want to let you know... it sounds like loads of fun as well!

You don't have to buy anything to participate. Just go visit the 12 blogs and see the various contests. I visited some and saw a photo contest, one where you need to guess what the children in an old photograph are thinking, one writing contest, one was something about finding a quote and writing about that. And there are more (I didn't visit them all).

They've also paired each blogger with a publisher, and Amy Beth from My Smoky Mtn. Homeschool will be writing something concerning my Math Mammoth books during the contest.

Here's a complete list of the 12 participating blogs:

www.Homeschoolblogger.com/01charger

www.Homeschoolblogger.com/ReviewsbyHeidi

www.homeschoolblogger.com/eclecticeducation

lifeonwindyridge.blogspot.com

www.homesteadblogger.com/TexasRose

triviumacademy.blogspot.com

tnmomwith3kids.wordpress.com

www.homesteadblogger.com/simplefolk

homeschoolblogger.com/mysmokymtnhomeschool

www.homeschoolblogger.com/ClassicalEducation4Me

janne.cc/blog

www.homeschoolblogger.com/Ruth

Oh, almost forgot: you can only enter 2 of the 12 contests.

Kamis, 06 Desember 2007

Algebraic thinking

I downloaded the "balance" worksheet freebie, and daughter liked it. We homeschool and she would be in fifth grade this year if she were in public school. ... My question is about the balance worksheets - where would there be more of that? Stuff that does groundwork for algebraic thinking?

It's not just balance problems that prepare a child for algebra. These are important factors also:
  • a good number sense (e.g. mental math)

  • understanding of the four basic operations, for example how the opposite operations work. Another example: understanding that a division with remainder such as 50 ÷ 6 = 8 R2 is "turned around" with multiplication and addition: 8 × 6 + 2 = 50.

  • a good command of fraction and decimal operations. Understanding the close connection between fractions and division.

  • understanding the concepts of ratio and percent.


You can also simply write her more problems with an unknown. For example:

Write 7 + x = 28 and similar ones, like 12 + x = 99 and harder numbers.

x − 9 = 9 and notice how this is "solved" by adding.

6 − x = 4 and then harder numbers.

The same with multiplication and division.

I would also add one more thing that prepares children for algebra: good word problems -- not such that only require one operation to solve.

Singapore math's word problem booklets are told to be good, and here are some other (free) word problem websites.

In fact, soon I want to talk a little more about good word problems based on a paper I'm currently reading.

Selasa, 04 Desember 2007

The snowy edition of Carnival of Homeschooling

.... is posted at Dewey's Treehouse. Mama Squirrel has done a fine job, go check it out!

Carnival of Homeschooling 101: Snowed in edition