The above is a copy of Don's watercolor painting of The Nautilus shell; it is Don's logo. The shell is beautiful,  its shape a mathematical curve, and can be obtained from conchking. Also see the equation for the shell ,  making a spiral , IES java applet making a Nautilus, Xah Lee's work on spirals (and other curves) and student work on the growth of the Nautilus (chapter 6), and Don compares the Spirals of the Nautilus shell, the Fibonacci numbers, and the Equal Tempered Chromatic Music Scale .

ようこそ; WELCOME ! عَلَى الرُّحْبِ والسَّعَة ; 환영받는; ¡bienvenido a casa!; 迎; hoan nghênh; karibu!; aa'o bhagat karna; Willkommen; Selamat Datang; Aapka swagat hai; Sawasdee Krub; kumusta, ; Makati, Phililppines; New Delhi, India; Shinjuku, Japan; La Crosse, WI; Champaign, IL; Gardendale, TX;  2 CD set to Maylasia;  2 CD set to Singapore; Leicester, UK; Bangkok Thailand, 21 visitors/month averaging 1 hr 53 min on Don's site- a record!); London, ON, Canada; ..and all the world.  Over the past month (May 2009), at least 1 person came from every state in the US to Don's website; the most came from Illinois with 131. About 1400 people from 56 countries around the world, came to Don's website, as shown in Google Analytics.

 Refreshing insights into the learning and doing of some important mathematics, by young people (while doing lots of arithmetic, using many hands-on materials, science to math activities, and the non-trivial use of calculators and computers)-- for children, as well as adults. Don assumes only that a student can count.

Don's keys:

visualization,

look for patterns,

learn to learn

  Don Cohen-The Mathman site search by Google;   try "Patterns in graphs", or "iteration", or "Alex", ..

Try sample problems from Don's books, by chapter!

The Math Program

Excellent math instruction for K-12, and all abilities - for 33 years!
Make Summer a big help for your children- prepare for Fall classes; move ahead;  understand math much better; learn not to fear math; build confidence; get an early start on fractions, algebra, geometry, trig, and calculus (ages 7 and up!); 

prepare for UNI (SSAT), SAT+1&2, ACT, AP Calc, GED, GRE TESTS. 

Adults, parents, and teachers, are also welcome to come to learn mathematics.

Call  today,

Don Cohen  217.356.4761    

email Don today at doncohenmathman@gmail.com

Don's address: 809 Stratford Dr. Champaign, IL 61821- 4140

Google map of Don's house

Nanako, at ages 8 and 9, came from Japan for a week each of the last 2 summers. Don uses a sunflower stalk for Nanako to obtain the Fibonacci numbers. Finding  their ratios, she got an infinite sequence which approaches the Golden Mean (see ch.7 in Don's worksheet book). 

               

 Don is now accepting a limited number of students from afar, to come to Champaign to work with him on his Calculus For Young People program. 

Don is also accepting a limited number of students to work in his 
Calculus By and For Young People-Worksheets book with him, via email.

Exciting news- all the time!  

 

Order Don's 2 CD set with all his materials, @$70.95,

via Google Checkout or PayPal Checkout below or check or money order. 

Note: Shipping is FREE in the US (IL add 7 3/4% tax).

To ship outside U.S. email Don for S&H

Google Checkout

Don's 2 disk set Calculus For Young People, ISBN 9780977949311, is now listed on Google Book Search

PayPal Checkout
Acceptance Mark

Don's Calculus materials
19 June 2009 Don received this email:

Dear Don,
I don´t know if you remember us, but we came to see you for a week about six years ago.  My son Johann was five years old.  I have thought of you so often and how you inspired our family. Johann loves math and now our younger son Tristann is also learning to love math through his interest with origami.  I don´t know why we didn´t keep in touch with you, but somehow life got in the way.

I would like to be able to bring my kids back, I know they would love it.  I am so impressed with how you teach and your love of math.  I would love to hear from you.

Warmly,
Svava (CA)

7 June 2009 A conversation between Maya, 8 years old, Don, a TI-84 plus calculator, and WolframAlpha, to find the sum of 2+1/2+4+1/4
4 June 2009 Just so you know that Don is not perfect. From a note to Don from one of his mothers: Mr. Cohen, Could you work on some basics with Sarah. Addition, subtraction, multiplication, division, counting money, and word problems. She still got a C-  in Math.. Thanks, Frances C. [Sarah is continuing to work with Don through part of the summer].
2 June 2009 From a note to Don from one of his fathers: Don, The kids had a very good year with you. In addition to all the things they learned about geometry, numbers and puzzles, I think they've absorbed the most important idea: math is fun!

I hope you have a good summer, and I know the kids look forward to seeing you again in the fall.- Charles

22 May 2009 From a note to Don from one of his mothers: "Thanks for helping Jesse to his "A" in math! Fondly, K. [Jesse was taking algebra when he started with Don in Dec. '08 with an "E" (for failing- of course he didn't hand in homework), and by the end of January, a month later, he got an "A" and continued that until the end of the school year!]
7 May 2009
- a note from a parent of 3 of  Don’s students, along with a check for May:
Hi Don! I wanted to mention that we might send Jack to you this summer- and have Joe take the summer off. If Joe’s schedule allows him to go to you, we’ll send both boys.

You have made a huge difference in Joe’s life! Certainly his confidence and skills in math have increased- but your (and Marilyn’s) influence goes beyond that. You model for him an attitude and approach to life that he very much admires. I believe it really does “take a village” to raise a child. I feel mighty good that you both are part of Joe’s “village”- that you have been a part of all of our children’s village. Thank you! Bernadette

1 May 2009

from: Maria Droujkova<droujkova@gmail.com>

subject: Changing Shapes With Matrices - in the Math Clubs!  

This is an activity designed by Don Cohen-The Mathman, in his book "Changing Shapes with Matrices." You can find some sample book problems here, and follow links to other Don's materials:  http://www.mathman.biz/html/probcswm.html

The general idea is to start with a simple "dot to dot" picture on a coordinate plane, and then apply a matrix transformation to coordinates of every dot.
Like many activities involving massive number crunching, it works much better on computers. [That’s why Don starts with a simple “doggie” with only 9 integral points, and limits students to only 1’s, 0’s and -1’s to form the transformation matrix, so there is not a lot of number crunching]. You can experiment with this applet, transforming a doggie, on Don's site [made by IES in Japan] at: http://www.mathman.biz/html/dogtrans6/changing_shapes_with_matrices%20ies6.html

…Kids could quickly test conjectures, such as: "What makes the shape flip? How can you stretch the shape more? What happens if you put opposite numbers in the matrix? Reciprocal fractions? Zeroes?" This was some excellent math by kids - the reason I love this activity so much.

…We did some very meaningful math and had a lot of fun with the activity. Don, thank you very much for your wonderful books, full of great activity ideas. 

For Maria’s complete article, go to  http://groups.google.com/group/naturalmath    

Thank you Maria, for sharing this activity with your google group.

28 April 2009 Don and his students Jay, Chris, and Elizabeth find a new number- the Dottie number
2 April 2009 Check out Don's granddaughter Tara and friend Tyler. on their world trip by bicycle at www.goingslowly.com - they started in Scotland and are in France at this time (23 June 2009)! See the article about them in the April 20 issue of The News-Gazette.
30 March 2009 From a note to Don from one of his mothers: Dear Mr. Cohen, ..We are  fortunate that Mildred was able to work with you this past year.. We will always happily recommend your services to others and would not hesitate to contact you in the future if we should find Mildred in need of additional math tutoring. Thanks for everything. T.C.
23 March 2009 from an email

Dear Don,

 ..Ashley received her letter of acceptance into the Radiology Program at Parkland College on Saturday, March 21, 2009 and is so excited about that!  Thank you again for assisting her with her Math!  If she ever needs any future tutoring, we would certainly give you a call.

Sincerely,
Julie (Mom)

20 March 2009 From Michael's Mom: Don, Thank you for working with Michael [8 months via email- see some of his work below]. Maybe we can come spend a few days in person with you this summer...

Michael is really enjoying your calculus worksheets. Thanks again!!  Sincerely, Theresa (WI)

26 February 2009 Dear Lori Johnson Morse, my friend and fellow math tutor wrote a little article about Don which was accepted on an eNY Times page- take a look.
18 February 2009 See Malcolm Gladwell's book Outliers The Story of Success. Chapter 8 is entitled: Rice Paddies and Math Tests. Lots of interesting connections and without knowing these, Don had his Calculus.. book translated into Japanese and it is doing much better in Japan than the original English version in the US.
2 February 2009   Email: “I heard about your product (2 disk CD set) from a homeschooling family that is registered with the same DL school [in Canada ] that my children are and they recommended it”.- Karen T., after she purchased same.
23 January 2009 Email from Don's Facebook file

Subject: Thank You! 

I just wanted to drop you a line and tell you how much my girls and I have enjoyed your math program. Last year we bought the Calculus program at our home school convention, and my girls have not put it down since. They are so excited about math and it has become their favorite subject. Thank you so much! Julie, GA

Thank you Julie, for sharing this wonderful information!

November, and 10 December 2008 Ann-Emily, 2nd grader, adds fractions using complex fractions and multiplies mixed numbers-WOW! (and Don never taught her how to do any of this)
 As a teacher, Don likes this quote by an anonymous writer who said: "We have not succeeded in answering all your problems. The answers we have found only serve to raise a whole set of new questions. In some ways we feel we are as confused as ever, but we believe we are confused on a higher level and about more important things".

Mathematics in Science: Michael has been working through Don's worksheet book and with Don via email, for about 8 months. In chapter 6 there is a diagram of hinged mirrors at left, below. Students are asked to look between the mirrors to see how many images of a red rod, say, that they see with the mirrors open at an angle of 90o (3 + the original=4). 

Michael made the diagram at the right below, using an angle of 60o  between the mirrors, and proceeded to show the path of the light rays as they leave the red rod, bounce off the mirrors (the angle of incidence equals the angle of reflection) and to go to the eye, He found the 6 images (5+original=6); and they all lie on the same circle!  And there is a rule here.                                                  

Fine job Michael!!

Fine applets to interact with -you need to download free Java program to view these:

     The Nautilus Shell applet done by Lori and Don - you need to download free, geogebra

    Area of triangle= limit of infinite series, applet done by Lori and Don - you need to download free, geogebra

     Changing Shapes With Matrices  applet done by IES in Japan to go with Don's book of this title

    The six trig functions in one picture applet done by IES in Japan- upon Don's recommendation

    The difference of 2 cubes (Maggie, 9 years old, builds a box..and does some algebra)- applet done by IES in Japan- upon Don's recommendation

    (a+bi)^(a+bi)^ ...  applet done by IES in Japan, inspired by Don's  problem of i^i^i... in his Worksheet Book, Chapter 11 -IES as usual, did a great job with this, ending up with fractals!

10 October 2008 Don received this note from the mother of her 11th grade student:

Dear Mr. Cohen

Thank you for being a teacher and an example to Elizabeth and other kids in math and in life. 

Pat

1 - 3 October 2008 Mathematics in Nature: Aaron, Don's grandson, brought him a sunflower head cut from his garden; it was about a foot in diameter. The seeds grow in spiral arrays in 2 directions. See the photo below that Don took of the sunflower head, then added the numbers. Maddie, a 5th grader, with Don, counted the rows of seeds in the one direction going clockwise around the sunflower head (starting and ending in the lower left of the picture). They colored the starting or first row red and every 10th row red, to help keep track of the counting. The rows bend sometimes, not perfect spirals, which makes it difficult to count. Then Don and some other students finished counting those and the rows in the second direction, again going clockwise around the sunflower head, coloring the starting or first row black and every 10th row black. 

There were 89 rows in the one direction and 55 rows in the other direction, both Fibonacci numbers, including 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ... see the pattern?

See the sample problems from chapter 7 in Don's worksheet book and you'll find that Don has his students use the infinite sequence of the Fibonacci numbers to get the ratios of these. They are working with infinite sequences, ratios, fractions, mixed numbers, division,  decimals, infinite repeating decimals and finding patterns. The infinite sequence of  ratios has a limit which turns out to be The Golden Mean or The Divine Proportion, 1.618033... which  equals (1+ Sqrt(5))/2. 

Don's son Brian made a beautiful, wooden 3-D diorama for the story written by Don's granddaughter Tara, for her UNI HS geometry class, at age 15, entitled  A Quest For The Sacred Golden Pineapple, Pine Cone and Artichoke.  The diorama includes 1.) a figurine of The Old Mathman holding a golden pineapple, made by Tara, within a dome, 2.) a watercolor painting by Tara and Don of The Old Mathman's house in the woods, and 3). a shelf underneath with a copy of Tara's story.

26 September 2008 Don received this email from the mother of a former student:

Hi Don,

For ages I have been thinking about getting in touch with you - and hope that this e-mail address still works. I'm not sure that you'll remember Andy from about 12-13 years ago, but if you do I thought I'd give you an update. He graduated from U of I with majors in math and physics in 2006 and then went on to grad school in physics at Harvard in the Fall of 2006. He finished his Masters in January 2008 and then decided that he really didn't want to be an experimental physicist. So, he's now on a 2-year leave from the program and working as an energy analyst for ___ in downtown Boston . He is very happy to be making $ and really engaged in his work. In fact, he seems all grown up and indeed an adult.

I hope that you are well and still the mathman. Andy really benefited from working with you, and I always enjoyed talking with you too. Have a good October.

Chris

It has been 20 years (1988) since Don published his book Calculus By and For Young People (ages 7, yes 7 and up) . It was reviewed in the Dec. 1988 issue of Scientific American magazine. It is still selling, now on CD Rom, and on his 2-disk CD set Calculus For Young People . Then came Calculus By and For Young People-Worksheets with questions leading to the different ideas. Then 2 videos (Infinite Series and Iteration),  A Map To Calculus and Changing Shapes With Matrices. All items are now on his 2-disk CD set Calculus For Young People  

It has been 10 years (1998) since Kodansha Ltd. published the Japanese translation of the original book.

Mr. Sasaki at Kodansha Ltd., wrote to Don a month after they published the Japanese translation of Don's book Calculus By and For Young People (ages 7, yes 7 and up) in 1998: "We can say that your method was accepted to Japanese people as a kind of new text in which they could learn and understand math much more than ever before".

Needless to say, Don's Japanese book has sold much better in 10 years, than the original English version in the US in 20 years!

Back in 1988, Don felt his book was 20 years ahead of its time, and now in 2008 he still feels it is 20 years ahead of the math taught in schools- of course it's not just the book, but also his methods of teaching.

10 September 2008- 20 February 2009 Erin has made 16- 3x3x3 cubes with the 7 Soma pieces and drawn the layers to help others make a cube. Erin is amazing; she keeps coming up with new ones, and can tell if it is different from the others- of course she checks them!
22 August 2008 From Michael's Mom: "Do you like to see the parents involved..?" Don's response: Yes, even to have you child explain something to you. I had Sheri as a 4-6th grader; now she is a 12th grader taking Calculus. I worked with her for about 3 hrs individually over the last month (August 2008). Today, a week into her calculus class, she told me 'What we did the last 3 weeks (derivatives), the teacher did with my class in one day, and I was like the only one in the class that understood what she was talking about! It really helped for me to talk with you about the problems as I worked on them'. On Don's main page, search "Sheri" to see what she did as a 4th-6th grader!
11 August 2008 Sara & Maya, age 7 (twins), find Patterns in division
21 July 2008 Alex, a 2nd grader, sees an infinite series!!!
27 June 2008 Mom and Dad with their 6 children, drove down from North of Chicago. Mom and 4 children, 3 girls and 1 boy, worked with Don for 2 hours, while Dad and their two youngest children went off to the park. Click here to see what they worked on.
17 June 2008 Don received this thank you note from Paul, who came to Don from 3rd grade through 12th grade:
Dear Mr. Cohen,
Thank you very much for the beautiful graduation card, the gift card to Pages For all Ages, and for attending graduation. Even more significantly, thank you for providing a strong foundation in mathematics and for helping me through subjects I found especially difficult. Your innovative approaches and teaching styles kept math interesting and fun, while the teaching methods in school made it dull and repetitive. This approach has been something that I can apply to different aspects of my life, by looking at a topic from a different angle, I am able to much more thoroughly comprehend the subject.
Once again, thank you so much for all you've done.
Sincerely, Paul
Thank you Paul, for your dedication to excellence and being a wonderful human being, and to Mom and Dad, for making it all possible! You all have helped make the last 10 years of my teaching very enjoyable.
16-21 June 2008 Nanako came from Japan again to work with Don!
3 May 2008 Don & Marilyn were in Albany, NY to accept his 2008 Excellence in Education award- see the program and Don after his speech . Don wants to thank the Alumni Association of UAlbany, SUNY, his friends, students and parents of his students who wrote to support his nomination. Don realizes though, that this award is not as important as his work with individual students over the years-and for that he is most grateful. It has been a great ride!

While in Albany, he and Marilyn drove past Bethlehem Central Junior High School (now Middle School) where Don started his math-teaching career in 1954!

April 2008 Margaret, an 8th grader, asks a great question!
Don's  2-disk CD set,  "Calculus For Young People (2 CD set)", ISBN 9780977949311, contains all of Don’s materials -3 books, 2 videos, map, & poster, listed here: 

1. "Calculus By and For Young People (ages 7, yes 7 and up)”
2. "Calculus By and For Young People--Worksheets"
3. "A Map to Calculus"-- a 15" x 18" flowchart, overview
4. Video #1 "Infinite Series By and For 6 year-olds and up"
5. Video #2 "Iteration to Infinite Sequences with 6 to 11 year-olds"
6. "Changing Shapes With Matrices"
7. “On thinking About and Doing Mathematics”-11x14” poster  

The 2-disk CD ROM set above, for PC and Mac users, sells for $70.95 on Google Checkout above. 

Note: Shipping on all items is FREE in the US, 

To outside U.S. email Don for S&H.

------------

Besides the two-disk CD set above,
Don will continue to sell these, paid via PayPal/check only:

"Calculus By and For Young People (ages 7, yes 7 and up)"    (CD-ROM); ISBN 9780977949304 ______$23.95 (also on 2 CD set)


 "Calculus By and For Young People--Worksheets" (CD-ROM);
        ISBN 9780962167478 ___________$35.95 (also on 2 CD set)


"A Map to Calculus"-- a 15" x 18" poster-flowchart;
        ISBN 9780962167485___________ $13.95 (also on 2 CD set)


"Changing Shapes With Matrices" (paper);
        ISBN 9780962167430 ____SALE______$6.95 (also on 2 CD set)

See what Rainbow Resource Center says about Don's materials.

1 January 2008 What a way to start the new year! Don spoke to Jonathan (now 26 years old) and his Mom and Dad who are in CT.  Jonathan, at age 7, started working in Don's book Calculus By and For Young People (ages 7, yes 7 and up), with his Mom acting as his secretary. She sent his work to Don. (This started Don on his Math By Mail/Email Program). That and the following summer, his Dad brought him to Champaign for a week to work with Don. Some of Jonathan's work is in Don's worksheet book and he is on his videotapes.

Jonathan has finished the course work for his PH.D. in High Energy Physics and is working on his dissertation, which he plans to finish next year!

Don is very pleased when his students do well!

What a wonderful year 2007 has been. If we could only have Peace, and no one should go hungry!

28 December 2007: Don and his wife Marilyn celebrated their 55th wedding anniversary today!

 Marilyn and Don Cohen are excited about their part-time work as Shaklee Distributors and users of many Shaklee “in harmony with nature” products-100% guaranteed -nutritional supplements including the new VITALIZER, Get Clean, Cinch inch-loss program, air purifier and more!- and they want to share these with you. Please take a look at their Shaklee website if you want to feel better, want a healthy home, a healthy planet, and bring in some extra money.
 19 July 2007: Don received this email  from a parent who had purchased his 2-disc CD set: "..I just wanted to say thank you again for inspiring me and helping me realize that kids can understand and do so much more with math than many people are willing to believe..". 
13 June 2007: Leah's Mom called to tell Don that Leah got into UNI High School and would continue to work with Don in August when she returns to Champaign- Congratulations Leah!!

3 March 2007: Geometric Sequences and the 88 Keys on a Piano by Don

17 February 2007 Five views of  Don's Math Room - where it all happens!   

9 February 2007 Don received an order for his 2-disc CD ROM set from Moscow, Russia !!

7 February 2007 Don spoke to Loralee Johnson at "4 Your Mind" and told people during the interview that Loralee is selling Don's materials in Edmonton, Alberta, Canada and can be reached at 1-780-485-0969 or ljohnson@shaw.c

 Check out  Lori's website for her "MathHead Tutoring Inc."

“..You wrote an amazing book (Don's worksheet book).  Every week what my kids learn puts smiles on their faces.  It makes me smile, too.  You make people smile because they can understand math better.  It’s a gift and you share it with as many people as you can!  And I am having a blast following in your footsteps.  Much, much thanks! Lori”. KC, MO

See the internet links to Don's website and references to his books from around the world!

Homeschooling math by Don Cohen

                   “ ..Two roads diverged in a wood, and I - -
            I took the one less traveled by,
            And that has made all the difference.”

From The Road Not Taken  by Robert Frost. Don feels that what he has done is not the usual, and something that has touched many people, young and old, around the world, very positively, and has been very rewarding-  and that has made all the difference in his life!

 To get around on Don's site, choose from the menu below:

 

Don's Materials Will Teach You To:
Discover
Patterns
-New discoveries &

Patterns in Mathematics

Try sample problems from Don's worksheet book, by chapter!

Don's Materials
(all published and copyrighted by
Don Cohen-The Mathman)

Get Ready for Calculus
  1. Book: "Calculus By and For Young People (ages 7, yes 7 and up)" (CD-ROM)
  2. Worksheet book: "Calculus By and For Young People - Worksheets" (CD-ROM) & Table of Contents of books 1 & 2
  3. Videotape #1: "Infinite Series"
  4. Videotape #2: "Iteration"
  5. "A Map to Calculus"
  6. "Changing Shapes with Matrices"
     
  7. All of Don's materials are on a 2 disk CD set (see above)

 Science to math activities
The non-trivial use of Calculators and Computers in Don's materials
The important mathematics
The importance of guessing
Patterns in Mathematics

Visualize
Mathematics
Learn to
Learn -
Tessa at 5 works with Grandpa ! "When Grandma talks, everyone listens!"		  
What parents, teachers, kids, Martin Gardner, Morris Klein, W.W. Sawyer, the MAA, the ASCD, Kodansha, Mary Pride in her 'Big Book of Home Learning', the July/Aug. 2000 issue of The Home Education Magazine, The Math Forum.. say about Don's materials
On Thinking About and Doing Mathematics
Who was that Mathman?
'The Math Program'- Don and Jerry's great way of teaching math & loving it! (and what parents and students say about The Math Program)
How other sites use Don's ideas & his website
Don's Favorite Places on the WWW
Puzzles, Games, & Hands-On Activities Don Uses With Students
After 45 years of teaching math & parenting..
Links to this website- how many now ?
Don's materials are for grades K-12, ages 6-8 with adult help, up through pre-calculus students, adults, teachers, teachers of teachers, and parents!

Send email to Don Cohen concerning his 'Math by Mail/Email' with IM and video, coming to Champaign to work with him , ways he could improve his web site, or other issues. count traffic people have come in, peeked, glanced, shook, were curious, skeptical, impressed, excited, thought about what their children are doing in school or as homeschooled, tried a problem, solved a problem, emailed Don, called Don, ordered his material, .. since June 6, 1996. Notice, this site slipped past 200,000 visitors in early  2004- in less than 8 years!
                 Thank you for stopping, do try some problems before you go!

Don's web site was designed and started by one of his former students, Jennifer, while at MIT, and continued & maintained by Don, with some help from his grandson, Lian.