How to picture an exponent

While I’m easily amused by math humor, I rarely actually laugh out loud after reading a comic strip. That said, I laughed heartily after reading this one.

Source: https://xkcd.com/2283/

Engaging students: Making and interpreting bar charts, frequency charts, pie charts, and histograms

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 Johnny Aviles. His topic, from Pre-Algebra: making and interpreting bar charts, frequency charts, pie charts, and histograms.

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

I would create a project where my students would make and interpreting bar charts, frequency charts, pie charts, and histograms. First, I would begin by using the class as data by asking them questions and use a specific chart for each question. For example, I would ask “who here is Team iPhone? Team Android? or who doesn’t care?” Essentially, I will be separating the class in select groups based on their preference of phone. I will then create a pie chart of the class based on their choice. I then would do more examples of the other charts and explain the purpose of each one and when to use it. After some more examples and practice for them to familiarize themselves with the charts, I will assign the project. I would then divide the class into 4 groups and evenly assign a chart to each student to find a real-world example to apply and create their own specified chart that they’ll present. (I divide the class to ensure that every chart gets represented.) The purpose of the project is for all the students to not only be exposed to all the charts but to also apply them and understand the use for each one.

B1. How can this topic be used in your students’ future courses in mathematics or science?

In terms of mathematics, bar charts, frequency charts, pie charts, and histograms are very essential forms of data. These charts are widely used in nearly every future math or science course of students. As appose of a large spreadsheet of data that is hard to interpret, this topic provides a more organized and visual way to provide that collected data and to find useful information. A great example of using this topic is statistics. a spread sheet in given and then transformed in the form of a histogram that would give information of its distribution. With this chart, one can find things such as mean and standard deviation. Statistics also test hypothesis that require data to decide whether or not a certain drug would be effective based on data from frequency charts or histograms. These charts are also widely used in science. They can record the population of a given species, growth of bacteria in a given time, surveys, etc. There are endless possibilities in which these graphs can be applied in students’ future subjects.

C3. How has this topic appeared in the news?

With the vast categories the news covers, there are many examples where bar charts, frequency charts, pie charts, and histograms have been used. The news is for the common people and the common person has socially acquired a short attention span. The news can’t just give a sheet of numbers and expect people to know what it means and let alone look at it. These charts are provided for everyone to be given vast amounts of data gathered in aesthetically pleasing chart that can be quickly interpreted. The weather uses data from previous years to predict what we could be facing in terms of temperature and rain on any given month or season. Sports are all stats that have been recorded and can predict the outcomes of future games and players stats. When a top new story unravels, news channels are quick to look up stats that relate to story and compare data for the viewer. These charts appear in the news frequently and are vital to be comprehended to future students.

A Clean Calculus Joke

The change of position over time is velocity.

The change of velocity over time is acceleration.

The change of acceleration over time is jerk.

And the change of jerk over time is an election.d

Engaging students: Finding points on the coordinate plane

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 Tiger Hersh. His topic, from Pre-Algebra: finding points on the coordinate plane.

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

To find a point on a 2-D coordinate plane we would need to have an x-axis and y-axis. Many things in the real world could act as a coordinate plane and that could also be used to create an activity or project. One of those things could be where the students could use a Nerf gun and fire it at a wall with a coordinate plane. This activity would not only be engaging for students but also help them understand how to plot the points on a coordinate plane, but also show students how to find the point on the coordinate plane.

Students will group up and take turns firing darts at a wall that would have a coordinate plane on it. Each group will have different color darts to indicate where each group has plotted their point. Each student in each group will fire two darts at the coordinate plane; After each student has finished plotting their points they will approximate the point and record it down on their worksheet.

Curr1 : How can this topic be used in your students’ future courses in mathematics or science?

Plotting points on a 2-D coordinate plane is used in almost every future course in mathematics. You can observe the usage of 2-D coordinate planes in Geometry, Algebra 1, Algebra 2, Pre-Cal, and so on.
In Geometry you can plot the points of a triangle on the coordinate plane to then find the distance between them with the distance formula or you could find the midpoint between each point using the midpoint formula. These are only some examples that plot points on the 2-D coordinate plane.

In Algebra 1/2 you can see that you can find the slope between two points using the slope equation. You can also use this concept to plot points for equations that involve the slope-intercept form, polynomials, the unit circle, shapes, etc. The points that are plotted could also show what is happening over a period of time and also give us an idea what the equation is trying to tell us.

In Pre-cal you plot points on a coordinate plane in the equation $x^2+y^2=1$ to form the unit circle and also plot points when you have to rotate or transform a shape or equation.

Cul1 : How has this topic appeared in pop culture (movies, TV, current music, video games, etc.)?

The game Starcraft 2 is a real-time strategy (RTS) game where you have to build an economy to fuel an army and beat the opponent by destroying their infrastructure, economy, or army. Interestingly when you build your building you notice that you are building on a 2-D coordinate plane.

The game itself is in its own 2-D coordinate plane where you have to plan where to move at certain points and also place your buildings at certain points to either block off a ramp or create a concave for your units so that they are able to deal more damage towards the opponent. There are also times in the game where you have to keep in mind about key parts in the map where your opponent is, where your next bases are, where proxies are, and where to set up counter attacks on your opponent.

Visualizing One Million vs. One Billion

From the YouTube description: “There are lots of ways to compare a million to a billion, but most of them use volume. And I think that’s a mistake, because volume just isn’t something the human brain is great at. So instead, here’s the difference between a million and a billion, in a more one-dimensional way: distance.”

The video is more than an hour long, which is the point. In the last minute of the video, he mentions what a trillion would be in the same scenario.

Engaging students: The field axioms

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 Andrew Sansom. His topic, from Pre-Algebra: the field axioms of arithmetic (the distributive law, the commutativity and associativity of addition and multiplication, etc.).

Algebra, from one perspective, is the use of numbers’ and operations’ properties to manipulate expressions. Some of these properties, called the field axioms, are crucial to being able to easily solve equations. These properties include associativity, commutativity, distributivity, identity, and inverse. To better appreciate how these properties are so helpful in algebra, it is useful to explore some examples of operations that do not obey these laws.

A1. What interesting (i.e., uncontrived) word problems using this topic can your students do now?

Example 1: The Average (Mean) is Not Associative

Part 1
A math teacher Mrs. Taylor instructs a class of three students: Alice, Bob, and Charlie. The class took an exam last week, but Charlie was sick and missed the test, so he took it today. Mrs. Taylor promised the class that if the class average on the exam was high enough, she would give them all candy. If Alice scored a 96 and Bob scored an 83, what was the class average (the average of those two students) after the first day of the exam?

mean(A,B)= $\frac{(A+B}{2}$ =

Part 2
After Charlie took the exam (he scored an 89), Mrs. Taylor wanted to know if she had to calculate the average from scratch (i.e. add all three scores and divide by three), or if she could just average the previous mean and Charlie’s score (i.e. add your answer from part 1 and Charlie’s score and divide by 2), since she already had done some arithmetic and didn’t want to waste time. Would she find the same answer if she tried both methods? If not, which one is correct? Why?
mean(mean(A,B),C)= $\frac{ \frac{A+B}{2} +C}{2}$ =

mean(A,B)= $\frac{A+B+C}{3}$ =

Part 3
After her discovery in Part 2, Mrs. Taylor is curious if she first found the mean of Bob and Charlie’s grades, then averaged it with Alice’s grade, if it would be the same as an answer above. Is it? Why or why not?

mean(A,mean(B,C))= $\frac{A+ \frac{B+C}{2} }{2}$ =

Part 4
What does it mean for an operation to be associative? How does this activity show that the average (mean) is not associative? Why does this mean you have to be extra careful when solving problems with averages?

Example 2: Subtraction is Not Commutative

Part 1
Mrs. Taylor likes to visit Alaska during the summer. When she arrived in Anchorage, it was 10F, but a snowstorm caused the temperature to drop by 21F. Write an equation with subtraction to find the new temperature the next day.

The next summer, when Mrs. Taylor arrives in Anchorage, it is 21F but the temperature drops 10F. Write an equation with subtraction to find the new temperature the next day.

Part 2
What does it mean for an operation to be commutative? Based on what you found in Part 1, is subtraction commutative? Why or why not? Why does that mean you need to be extra careful when solving problems with subtraction?

B2. How does this topic extend what your students should have learned in previous courses?

Prior to pre-algebra, students should be proficient in arithmetic. In that study, they should have been exposed to fact families, which are simple examples of the inverse elements of addition and multiplication. The field axioms generalize these ideas to other objects. Students also should have realized that subtraction and division do not commute, though they likely never used that name. They also likely realized that addition by 0 or multiplication by 1 do not affect the value of the other element. By learning the names of these different properties, students build upon their prior experience to be able to label and acknowledge when these properties appear in other contexts.

B1. How can this topic be used in your students’ future courses in mathematics or science?

Although high school students will spend most of their time working in fields, instead of other algebraic structures such as non-Abelian groups or noncommutative rings, an appreciation and awareness of the field axioms while studying pre-algebra will prepare them for solving equations involving exponents (for example, intuitively questioning whether 2^x=x^2, which are trivially different, but not obvious to the novice). Furthermore, most Algebra II classes do briefly study Matrix Algebra, which is noncommutative (i.e. matrix multiplication does not commute), which causes many interesting conundrums for the uninitiated student while trying to solve problems. This appreciation of the field axioms prepares them for later study in Linear Algebra and Abstract Algebra. Outside of their math classes, vector fields form a critical part of physics, even at the high school level. Although most high school students do not realize it, they have to use the field axioms all the time to solve physics problems.

References:
Use of the mean as a simple example of a non-associative operation courtesy of StackExchange user “Accumulation” on the thread “Non-Associative Operations” (https://math.stackexchange.com/a/2892589)

Living Proof: Stories of Resilience Along the Mathematical Journey

Quoting shamelessly from https://blogs.ams.org/inclusionexclusion/2019/06/26/living-proof-a-must-read/:

The AMS and MAA have recently published a phenomenal collection of essays entitled “Living Proof: Stories of Resilience Along the Mathematical Journey”, edited by Allison K. Henrich, Emille D. Lawrence, Matthew A. Pons, and David G. Taylor. The book is free, and features an astounding group of contributing authors. The stories are organized around common themes in the experiences. Part I is about math getting hard and people hitting a wall. Part II is about struggling to belong in math (and is particularly well aligned with the goals of this blog). Part III is about persevering through and overcoming difficulties. And Part IV is about the sometimes challenge of integrating our mathematical identities with the rest of our lives.

I’ve read this compendium of 41 two- and three-page essays myself, and I highly recommend it as a way of encouraging young mathematician to persist along the journey.

Mathematics is about wonder, creativity and fun, so let’s teach it that way

I enjoyed this opinion piece at phys.org about project-based instruction in mathematics. A sample quote:

Mathematician Jo Boaler from the Stanford Graduate School of Education says that a “wide gulf between real mathematics and school mathematics is at the heart of the math problems we face in school education.”

Of the subject of mathematics, Boaler notes that: “Students will typically say it is a subject of calculations, procedures, or rules. But when we ask mathematicians what math is, they will say it is the study of patterns that is an aesthetic, creative, and beautiful subject. Why are these descriptions so different?”

She points out the same gulf isn’t seen if people ask students and English-literature professors what literature is about.

In the process of constructing the RabbitMath curriculum, problems or activities are included when team members find them engaging and a challenge to their intellect and imagination. Following the analogy with literature, we call the models we are working with mathematical novels.

Students Find Glaring Discrepancy in US News Rankings

Despite its hopelessly flawed methodology, U.S. News & World Report continues to sell magazines with its lists of Top 25 or Top 100 universities in various categories. Some universities who don’t play along, like Reed College, have long suspected that their rankings are penalized. So I enjoyed this press release from Reed College about statistics students who reverse-engineered the rankings to measure the magnitude of this penalty. The results are startling: while Reed was officially ranked #90, the formula should have them at about #38. In one glaring example, the magazine underestimated the college’s financial resources by over 100 spots even though this information the magazine could have obtained this information from free government databases instead of their survey.