Thursday, December 16, 2021

Post 2 of Wallly's Math Books: Fundamental Laws and Operations

This is the second post of a series of blogs devoted to my grandfather Wally's college freshmen math textbooks. One of the books Wally used was called Advanced Algebra. It was published in 1925 and in the preface it states the book is designed for students who have had one or two years of college algebra.  In addition, it states "The syllabi of the College Entrance Board, of the Regents of the State of New York, and of practically all states have been covered." This makes me wonder if there are college math texts today that take the New York Regents or Common Core Standards into account when designing their textbook.

In the previous blog post, I encourgaed people to try the following problem.  In addition to posting on twitter, I linked the blog post to the "Higher Education Learning Collective" Facebook group and was told by some that this problem was too easy to be a college level problem.  Here was that problem.

Problem 1: Prove that "The sum of the squares of any two unequal real numbers is greater than twice their product.  That is if a ≠ b, a2 + b2 > 2ab."  

Here is essentially the algebraic proof as given in the textbook: 

Given: a ≠ b, we know that a - b ≠ 0.  Squaring both sides gives  a2 - 2ab+ b2 > 0 and that means that a2 + b2  > 2ab.

Here is a way to visually see that the sum of the areas of two squares is more than double the area of a rectangle formed by the sides of the squares by using Desmos - a much more dynamic and visually appealing proof.


And here's a link to the original Desmos page that I used to create the video above: https://www.desmos.com/calculator/r6p2hpdplf


grapefruit Problem 2: This problem comes from pg. 28 of the Chapter 1 Fundamental Laws and Operations.

Although it doesn't appear to have been assigned to my grandfather and his classmates, it seemed like a interesting problem to solve. In fact, it is problem that I could see myself giving to my MATH 120 (Math for Teaching) students on the first day of class just to see what problem solving strategies they might use.

A man bought a certain number of grapefruit for $1.04. After throwing away 4 bad ones, he sold the others for 6 cents apiece more than he paid for them and made a profit of 22 cents. How many did he buy, and what did he pay for each?

How would you solve this problem?  Are there any generalizations you can draw?  Feel free to post in the comments of this blog post.  We'll look at at least two approaches to this problem in my next post.









Sunday, November 28, 2021

Post 1 of Wally's Math Books: The Syllabus + Problem 1

As I opened up my grandfather's math books - Advanced Algebra by Edgerton and Carpenter, published in 1925 and Plane Analytic Geometry by Barnett, published in 1927 - I saw a piece of paper folded up.  I carefully opened it and realized it was the course syllabus! How exciting to see how a syllabus from the fall of 1927 compares to the current syllabi I write for the math classes I teach.  Before you read my observations about this document, I encourage you to look at it yourself.  Zoom in.  What do you notice? What do you wonder?  Feel free to add a comment to this blog post.

Math 22 Syllabus from 1927

What I Noticed 

The paragraph at the top of the paper contains many instructions found in a typical syllabus. 

  1. Time Spent Outside of Class - It says that each assignment "merits two hours of study and review". My syllabus says "You are expected to spend at least 7 hours outside of class working on problems or studying for this class." 
  2. Number of Classes Per Week - Although I don't see how long a class is on this syllabus, the class meets 4 times each week.  This would translate into 8 hours of work spent outside of class.  My class meets 3 times each week for 70 minutes each class period.  So, it is possible that the amount of in class time may be similar.
  3. Ask Questions and Get Help - It is clearly stated that the instructor Professor Waltz wants the students to ask questions during class and outside of class.  There is no mention of specific office hours.  Maybe office hours were a construct that became standard after 1927. 
  4. Saturday Help Sessions - There is time and a location for help.  Saturday at 9 AM would not go over well for most students. But then again, it is a time when all of them would be available.  We currently offer virtual help sessions 11 hours a week and every day of the week. except Saturday!

What I Wondered
  1. What problems should be done? The list of problems was outlined, but what did 5n, 2n mean?  As I looked in Wally's math books, I noticed that he had checkmarks beside certain problems.  Every 3rd problem or every 5th problem. So, this notation was to show multiples of a given value.
  2. Assessments Where there quizzes or exams?  It says "Final Tests" on class meeting #62.  Since it says "an average of A or B will exempt from final tests", there must be something that is being graded.  But what?
  3. Where are the problems found? There are two books listed and it looks like Plane Analytic Geometry book is used starting on October 31.  However, it is not clear that Advanced Algebra is the first book.  And does October 10 - 97(5, 8, 10) mean page number 97 and problems 5, 8 and 10 was the assignment on October 10th?  Maybe...but neither book has a page 97 with those problem numbers.
  4. What is up with the margins? What is the arithmetic that Wally did on the side?  It looks like these may be his grades in the class and he is averaging them.  Perhaps he is trying to be sure he is exempted from the "Final Tests".
What did you notice and wonder about the syllabus?

Problem 1: This is not a problem that was assigned, but whas listed as a theorem on page 70 of Advanced Algebra.  It states "The sum of the squares of any two unequal real numbers is greater than twice their product.  That is if a ≠ b, a2 + b2 > 2ab."  Feel free to create your own proof and upload it in the comments or on twitter.  Make it an algebraic proof or a proof without words.  I have already started to work on a way to visualize this with Desmos and will share my solution in the next post.



Sunday, November 21, 2021

Introducing the Series: Wally's Math Books


two math books from 1927

It's been some time since I last did a blog post. Looking back on my previous posts makes me realize that I miss writing about math and teaching math. It's a kind of therapy for me. Even if no one likes my post or comments on it, it is there for me to look back on later. And I have a sense of accomplishment when a post is done, without the need for peer review or endless edits.

(Speaking of peer review...an article I wrote on The Global Math Department was recently published in the NCTM Journal Mathematics Teacher: Learning and Teaching PK-12.  The article appeared in the "Ear to the Ground" section and can be accessed here.)

Now back to the regularly scheduled blog post...I have decided to do a series of posts related to my grandfather's math textbooks from his freshmen year of college at The University of Pittsburgh.  Those posts will start in a week or so and I plan to do a post each week.  I figure that I blogged each day of the school year in a #teach180 blog during the 2017-2018 school year and I can meet a goal of blogging once a week.  The textbooks are from 1927 (nearly 100 years old) and inside I found what appears to be a copy of the syllabus! Now if only I could figure out what problems were assigned.  If I can figure that out, I may work through the exact same problems my grandfather did.  If I can't figure out the syllabus, then I'll select problems that have some of Wally's annotations written beside them.

The books are seen in the image at the top of this blog along with some notes that he left for me.  Walter Rupp (or Wally) was a chemical engineering major and his first course in his freshmen year involved books in Advanced Algebra and Analytic Geometry.  These courses laid the foundation for him to graduate at the age of 20 and become a successful engineer for Esso (now Exxon-Mobil).  He helped to create oil refineries in the Caribbean in the 1930's and some of his work led to patents of oil refining processes.


       Book with note to author from her grandfather


                Note written on inside cover from grandfather to blog author

Monday, May 24, 2021

Summertime: Math Playtime with Desmos Art Project

Children learn so much and are so engaged in learning when they have time to play, experiment and fail.  Yes...failure is a part of the learning process, a challenging concept for many parents grounded in the "my-child-is-better-than-your-child" culture.  But without time to play, experiment and fail, I would not have learned the following items: HTML (which helps with writing this blog), embroidery stitches (learning chain stitches prior to YouTube can be challenging), and how to use Audacity to create audio files from the video files for the Global Math Department podcasts. Given time to experiment and play, there is much to be learned!

Image of chain stitch
Image from needlenthread.com
As a high school math teacher for over twenty-five years, parents would sometimes ask me, "What should my child do over the summer? Khan Academy? A specific workbook? Take a test prep course? Enroll in a math class so they can AP Calculus and not fall behind their peers?"  I would often turn the question back on them and ask, "What is your child interested in doing this summer?"  Often this led to a discussion of what colleges or majors the parents wanted for their 15-year-old child, without the child being present for the conversation.

In each of these conversations with parents, I wanted to respond, "Give your child time to play, experiment and fail this summer. Ask them what they would like to try to learn and encourage them to share their failures and successes with you."  Of course, parents still crave some sort of structure and want their children to continue to do some math over the summer.  If you are a parent looking for this structure or you are a high school teacher that has been told to give a "summer math assignment", you can give an this optional creative task of "Desmos Art Project (Summer 2021)."  A special thank you to Julie Reulbach for initially creating a version of this Activity Builder for easy curation of the student art projects and to Javier Cabezas for creating the modifying colors screen in the activity.

Note to parents and teachers new to Desmos: You will need to create a free account at desmos.com to see the activity and then "assign" the activity to your child or students. Click on the triangle to the right of the "Assign" button to create a "Single Session Code". Click on "Create Invitation Code" and "View Dashboard". Then, you can copy the code to give to your child or students.

For examples of art projects from the most recent Desmos art contest, go to https://www.desmos.com/art and encourage your child or students to submit their work in any future Desmos art contests.