# Engaging students: Rational and Irrational Numbers

In my capstone class for future secondary math teachers, I ask my students to come up with ideas for engaging their students with different topics in the secondary mathematics curriculum. In other words, the point of the assignment was not to devise a full-blown lesson plan on this topic. Instead, I asked my students to think about three different ways of getting their students interested in the topic in the first place.

I plan to share some of the best of these ideas on this blog (after asking my students’ permission, of course).

This student submission again comes from my former student Daniel Adkins. His topic, from Pre-Algebra: rational and irrational numbers.

What interesting (i.e., uncontrived) word problems using this topic can your students do now? (You may find resources such as http://www.spacemath.nasa.gov to be very helpful in this regard; feel free to suggest others.)

The largest hurdle to overcome in mathematics, is the introduction to foreign, and new concepts. Quite often, individuals are stuck with their “old math”. When a new object appears before them, they won’t play with it, or recognize that even though it’s new, it still works with what we already know. This is especially true when it comes to introducing concepts of new sets of numbers, such as the imaginary numbers, or irrational numbers. More often than not, when it comes to irrational numbers, students freeze up. I believe that the best way to prevent this, is to show that students already know a lot about this set. By taking it step by step and reminding students what they already know about rational numbers, you can show them they have known about irrational numbers in some form or fashion for quite some time.

A simple two step project would be to first introduce the concept of an irrational number, then the instructor can draw a circle with a marked radius, and say, this is my pizza pie. Now I want a piece of pizza pie, but when it comes to pieces of pizza pie, I’m particular. I want to proficiently partake of my pizza pie by partitioning it perfectly, to where each piece is equally cut. If all I know is the radius though, how can I know where to cut it? Eventually students will point out that by finding the circumference, and then dividing the circumference by how many pieces you want, you can make sure they’re all equal. At this point, point out that you have a ratio of pieces to circumference, but how did the students get to the circumference in the first place? 2*pi*r so that means the radius of a circle is in a ratio to its circumference right? So we can right pi as some sort of fraction correct?  If the students are aware that this isn’t possible, then the digging isn’t necessary, but if they aren’t ask them to try and write it as a fraction.

The second part of this exercise would be to emphasize nested sets. Divide the students up into 2-4 groups, and have a several Natural, whole, integer, rational, and irrational numbers written on pieces of colored paper (with each team having 1 color). Students will line up in front of “nestable” baskets spread out in front of them labeled by the different sets of numbers as listed above, and will one at a time aim for the smallest set that their number can fall in. After all the papers have been thrown, the papers will be collected and compared as a class, and each paper made in the correct basket will count as a point for that team. At the end of it all, put the numbers back in their baskets and show how the baskets can all fit inside of each other, except that the irrational and rational baskets are the same size, and so they can’t nest inside of each other. This can be emphasized by drawing it on the board. This exercise reminds students of what it means for sets to share qualities, and that irrational numbers don’t have the same qualities that rational numbers do.

What interesting things can you say about the people who contributed to the discovery and/or the development of this topic?

Throughout my high school career, it was never brought to my attention that there were conflicts within the history of math, or in fact that there even was a history of math. In fact, it wasn’t till my collegiate years that my classmates and I came to learn such things were at one point a problem, that math could have different viewpoints.

The individual who is credited with discovering irrational numbers is Hipassus of Metapontum. He was a philosopher who studied Pythagorean based concepts, and while trying to use the Pythagorean Theorem to solve for a ratio between a unit square’s side length and its diagonal, he learned that there wasn’t such a thing. At the time, the other Pythagorean philosophers believed that only positive rational numbers existed. So when Hipassus introduced his discovery to them, they weren’t exactly happy. The story varies, and no one may ever know what truly happened to him, but some of the more versed stories range from the other Pythagoreans simply killing him, to Pythagoras himself ostracized him, and upon the Gods discovering the abomination he discovered, they had him drowned by the sea to hide it away.

Regardless of the validity of these stories, it shows how discoveries like these can often cause turmoil in time periods.

Hipassus’s discovery caused such a drastic response because of two reasons; first off, it contradicted the core belief of Pythagoreans that Mathematics and geometry were indefinitely correlated, as in they were completely inseparable. But it also raised another problem that would eventually be brought up by another philosopher named Zeno. The problem was in the discrete vs. continuous argument, and how geometry couldn’t solve it. All in all, when Hipassus introduced this concept, it was met with malice. Many individuals would write this off as simply how things were “back then”, but a closer examination at something like imaginary numbers will reveal a similar pattern. It wasn’t until the Middle Ages when Middle Eastern mathematicians introduced concepts of algebra that irrational numbers became fully accepted within the mathematical community.

All in all, the stories behind things like irrational and imaginary numbers should be shared within schools much more often. Not only is it extremely interesting, and can convince students to do their own research, but it also shows that people were afraid to learn new thing, that these foreign concepts that are terrifying now, were terrifying to the people who discovered them too. It teaches students that instead of ostracizing others for bizarre concept, but instead to analyze them themselves. Because those bizarre concepts, may become commonplace. It shows students that Hipassus was on the right side of history, even though he was alone for quite a while.

References:

https://brilliant.org/wiki/history-of-irrational-numbers/

http://www-history.mcs.st-andrews.ac.uk/HistTopics/Arabic_mathematics.html

https://www.algebra.com/algebra/homework/Problems-with-consecutive-odd-even-integers/Problems-with-consecutive-odd-even-integers.faq.question.580533.html

# Engaging students: Absolute value

In my capstone class for future secondary math teachers, I ask my students to come up with ideas for engaging their students with different topics in the secondary mathematics curriculum. In other words, the point of the assignment was not to devise a full-blown lesson plan on this topic. Instead, I asked my students to think about three different ways of getting their students interested in the topic in the first place.

I plan to share some of the best of these ideas on this blog (after asking my students’ permission, of course).

This student submission again comes from my former student Dalia Rodriguez. Her topic, from Pre-Algebra: absolute value.

A2. How could you as a teacher create an activity or project that involves your topic?

In Finding Dory, her parents laid out sea shells on the ocean floor that lead to her parents. The sea shells were spread out in lines going around the house, the distance from the beginning shell to the house is always positive, even though they are in the left side (negative side). The teacher can tell the student that each sea shell represents 1 unit, as they see the length of the sea shells lines the students will think of these lines as positive numbers, no matter what direction the sea shells are coming from.

Students should have already learned about positive, negative integers, and distances. You can engage your student by asking them question and having a class discussion. Questions like:

“What is a positive integer?”

“What is a negative integer?”

“How do you measure distance?”

“Can distance be negative?”

These types of questions will scaffold student to get a base line idea of what absolute value is, but also allow them to remember what they already have learned. Allowing students to realize that their connections from past knowledge to new knowledge will let them better understand what they are learning. Having a class discussion on their previous knowledge will allow a teacher to see where there might be misconceptions and also see a base line where the students are at, or what they might need help at. A small review lesson from the teacher, after a discussion, will then clear up any final misconceptions and allow the class to move forward from the same starting position.

# Engaging students: Solving one-step algebra problems

In my capstone class for future secondary math teachers, I ask my students to come up with ideas for engaging their students with different topics in the secondary mathematics curriculum. In other words, the point of the assignment was not to devise a full-blown lesson plan on this topic. Instead, I asked my students to think about three different ways of getting their students interested in the topic in the first place.

I plan to share some of the best of these ideas on this blog (after asking my students’ permission, of course).

This student submission again comes from my former student Anna Park. Her topic, from Algebra: solving one-step algebra problems.

How could you as a teacher create an activity or project that involves your topic?

Bingo game:

The teacher will create a bingo sheet with a free space in the middle, and integers in the other spaces. These integers represent the answers to the word problems that the teacher will be putting on the board or projector screen. Each word problem will either be a one-step equation or a two-step equation. A one step equation involves only one step to solve for the variable, this means only one operation will be done on the equation. The goal is to have the variable by itself on the left side of the equal sign and the numbers on the right side of the equal sign. A two-step equation is similar to a one step equation. A two-step equation is where it takes only two steps to solve for the variable in the equation that has more than one operation. The goal is the same as a one-step equation.

How can this topic be used in your students’ future courses in mathematics or science?

1. In future courses students will need to know how to isolate a variable in an equation to receive its value. They will need to know how to graph equations and inequalities in future mathematics courses. From Algebra and on students will need to know how to solve for the value of a variable.
2. Students will also need to know how to create an equation given to them in word problems. Some of the classes that this will be needed for is Physics, geometry, algebra II, Pre-Calculus, Calculus, college courses..etc. Algebra is a tool for problem solving, and critical thinking. Word problems give real life examples of algebra and students will be able to apply this knowledge to real life situations and understand the problems given to them in future classes.

How can technology (YouTube, Khan Academy [khanacademy.org], Vi Hart, Geometers Sketchpad, graphing calculators, etc.) be used to effectively engage students with this topic?

1. Kolumath is a great youtube math channel that explains how to do certain math operations with great visual examples and clear explanations. The speaker talks clearly and is easy to understand, and the examples he uses ties in information the students have learned in previous courses. His visual examples allow students who struggle with picturing math functions to connect to the lesson.
2. This channel also gives definitions over the topic and any definition relatable to the operations done in the video.
3. Listed below are examples he uses on how to solve one-step and two-step equations. (References)

# Engaging students: Venn diagrams

In my capstone class for future secondary math teachers, I ask my students to come up with ideas for engaging their students with different topics in the secondary mathematics curriculum. In other words, the point of the assignment was not to devise a full-blown lesson plan on this topic. Instead, I asked my students to think about three different ways of getting their students interested in the topic in the first place.

I plan to share some of the best of these ideas on this blog (after asking my students’ permission, of course).

This student submission comes from my former student Amber Northcott. Her topic, from Probability: Venn diagrams.

How could you as a teacher create an activity or project that involves your topic?

There are a few activities you can do with Venn diagrams. One idea is for the first day of class you can put up a big poster with a Venn diagram on it or you can draw one on the board. One circle can be ‘loves math’, while the other is ‘do not like math’. Then of course the center where the two circles intertwine will be the students who love math, but yet don’t like it. When your students come into the room you can have them put their name where it seems fit. This way you can get to better know your students on the topic of math. Another idea is that when you get to a topic, for instance arithmetic and geometric sequences, you can create a giant poster Venn diagram or draw it on the board. Then you can have your students write one thing that either arithmetic has or geometric has or both of them have. Once each student has put up just one thing on the Venn diagram, you can start a class discussion on the Venn diagram. While the discussion goes on you may fix a couple things here and there or even add to it. At the end each student will have their own Venn diagram to fil out, so they can have it in their notes.

How can this topic be used in your students’ future courses in mathematics or science?

Venn diagrams are an easier way to compare and contrast two topics. It can help differentiate between the two topics. For example, how are geometric and arithmetic sequences different? Do they have anything in common? What do they have in common? This helps students identify the topics more thoroughly and helps them get a better understanding about each topic.

How has this topic appeared in the news.

Not too long ago Hillary Clinton posted a Venn diagram about gun control on twitter. In response she was getting mocked and criticized. A short article on thehill.com goes into the mockery by showing pictures of people’s tweets to Hillary Clinton. Some had two circles separate from each other with one stating people who know how to make Venn diagrams and the other one stating Hillary’s graphic design staff. The other article from the Washington Post actually goes through her Venn diagram and fixes errors. These errors include the data in the Venn diagram.

Letting students see this, would definitely cause a discussion. I think we can turn the discussion into whether or not we think the Venn diagram was wrong. By having this discussion, we can learn more about what the students know about Venn diagrams and shed more light on how we can use the Venn diagrams in many different ways for many different topics.

References

https://www.washingtonpost.com/news/the-fix/wp/2016/05/20/we-fixed-hillary-clintons-terrible-venn-diagram-on-gun-control/

http://thehill.com/blogs/ballot-box/presidential-races/280706-clinton-mocked-for-misuse-of-venn-diagram

# What I Learned by Reading “Gamma: Exploring Euler’s Constant” by Julian Havil: Index

I’m doing something that I should have done a long time ago: collecting a series of posts into one single post.

When I was researching for my series of posts on conditional convergence, especially examples related to the constant $\gamma$, the reference Gamma: Exploring Euler’s Constant by Julian Havil kept popping up. Finally, I decided to splurge for the book, expecting a decent popular account of this number. After all, I’m a professional mathematician, and I took a graduate level class in analytic number theory. In short, I don’t expect to learn a whole lot when reading a popular science book other than perhaps some new pedagogical insights.

Boy, was I wrong. As I turned every page, it seemed I hit a new factoid that I had not known before.

In this series, I’d like to compile some of my favorites along with the page numbers in the book — while giving the book a very high recommendation.

Part 1: The smallest value of $n$ so that $1 + \frac{1}{2} + \dots + \frac{1}{n} > 100$ (page 23).

Part 2: Except for a couple select values of $m, the sum $\frac{1}{m} + \frac{1}{m+1} + \dots + \frac{1}{n}$ is never an integer (pages 24-25).

Part 3: The sum of the reciprocals of the twin primes converges (page 30).

Part 4: Euler somehow calculated $\zeta(26)$ without a calculator (page 41).

Part 5: The integral called the Sophomore’s Dream (page 44).

Part 6: St. Augustine’s thoughts on mathematicians — in context, astrologers (page 65).

Part 7: The probability that two randomly selected integers have no common factors is $6/\pi^2$ (page 68).

Part 8: The series for quickly computing $\gamma$ to high precision (page 89).

Part 9: An observation about the formulas for $1^k + 2^k + \dots + n^k$ (page 81).

Part 10: A lower bound for the gap between successive primes (page 115).

Part 11: Two generalizations of $\gamma$ (page 117).

Part 12: Relating the harmonic series to meteorological records (page 125).

Part 13: The crossing-the-desert problem (page 127).

Part 14: The worm-on-a-rope problem (page 133).

Part 15: An amazingly nasty formula for the $n$th prime number (page 168).

Part 16: A heuristic argument for the form of the prime number theorem (page 172).

Part 17: Oops.

Part 18: The Riemann Hypothesis can be stated in a form that can be understood by high school students (page 207).

# The Running Nerd: The US Marathoner Who Is Also a Statistics Professor

I loved these articles about Jared Ward, an adjunct professor of statistics at BYU who also happens to be a genuine and certifiable jock… he finished the 2016 Olympic marathon in 6th place with a time of 2:11:30.

Ward started teaching at his alma mater after graduating from BYU with a master’s degree in statistics in April 2015…

Ward wrote his master’s thesis on the optimal pace strategy for the marathon. He analyzed data from the St. George Marathon, and compared the pace of runners who met the Boston Marathon qualifying time to those who did not.

The data showed that the successful runners had started the race conservatively, relative to their pace, and therefore had enough energy to take advantage of the downhill portions of the race.

Ward employs a similar pacing strategy, refusing to let his adrenaline trick him into running a faster pace than he can maintain.

And, in his own words,

[A]t BYU, on our cross-country field, on the guys side, there were maybe 20 guys on the team; half of them were statistics or econ majors. There was one year when we thought if we pooled together all of the runners from our statistics department, we could have a stab with just that group of guys at being a top-10 cross-country team in the nation…

To be a runner, it’s a very internally motivated sport. You’re out there running on the road, trying to run faster than you’ve ever run before, or longer than you’ve ever gone before. That leads to a lot of thinking and analyzing.We’re out there running, thinking about what we’re eating, what we need to eat, energy, weightlifting, how our body feels today, how it’s going to feel tomorrow with how much we run today. We’re gauging all of these efforts based on how we feel and trying to analyze how we feel and how we can best get ourselves ready for a race. As opposed to all the time on a soccer field, you’re listening to do a drill that your coach tells you to do, and then you go home.

I think we have a lot of time to think about what we are doing and how it impacts our performance. And statistics is the same way. It’s thinking about how numbers and data lead to answers to questions.

Yes, I think there’s probably some sort of connection there to nerds and runners.

# Computing e to Any Power: Index

I’m doing something that I should have done a long time ago: collecting a series of posts into one single post. The following links comprised my series examining one of Richard Feynman’s anecdotes about mentally computing $e^x$ for three different values of $x$.

Part 1: Feynman’s anecdote.

Part 2: Logarithm and antilogarithm tables from the 1940s.

Part 3: A closer look at Feynman’s computation of $e^{3.3}$.

Part 4: A closer look at Feynman’s computation of $e^{3}$.

Part 5: A closer look at Feynman’s computation of $e^{1.4}$.

# Faculty Office Hours

Kudos to Arizona State University for making this public service announcement.

# Lessons from teaching gifted elementary school students: Index (updated)

I’m doing something that I should have done a long time ago: collect past series of posts into a single, easy-to-reference post. The following posts formed my series on various lessons I’ve learned while trying to answer the questions posed by gifted elementary school students. (This is updated from my previous index.)

Part 1: A surprising pattern in some consecutive perfect squares.

Part 2: Calculating 2 to a very large exponent.

Part 3a: Calculating 2 to an even larger exponent.

Part 3b: An analysis of just how large this number actually is.

Part 4a: The chance of winning at BINGO in only four turns.

Part 4b: Pedagogical thoughts on one step of the calculation.

Part 4c: A complicated follow-up question.

Part 5a: Exponentiation is multiplication as multiplication is to addition. So, multiplication is to addition as addition is to what? (I offered the answer of incrementation, but it was rejected: addition requires two inputs, while incrementation only requires one.)

Part 5b: Why there is no binary operation that completes the above analogy.

Part 5c: Knuth’s up-arrow notation for writing very big numbers.

Part 5d: Graham’s number, reputed to be the largest number ever to appear in a mathematical proof.

Part 6a: Calculating $(255/256)^x$.

Part 6b: Solving $(255/256)^x = 1/2$ without a calculator.

Part 7a: Estimating the size of a 1000-pound hailstone.

Part 7b: Estimating the size a 1000-pound hailstone.

Part 8a: Statement of an usually triangle summing problem.

Part 8b: Solution using binomial coefficients.

Part 8c: Rearranging the series.

Part 8d: Reindexing to further rearrange the series.

Part 8e: Rewriting using binomial coefficients again.

Part 8f: Finally obtaining the numerical answer.

Part 8g: Extracting the square root of the answer by hand.

# A Natural Function with Discontinuities: Index

I’m doing something that I should have done a long time ago: collecting a series of posts into one single post. The following links comprised my series on a natural function that nevertheless has discontinuities.

Part 1: Introduction

Part 2: Derivation of this piecewise function, beginning.

Part 3: Derivation of the piecewise function, ending.