Starting with Differentiability

My AP Calculus BC students will be starting off the academic year with me already having a few months of calculus under their belt.  They should already have a good understanding of limits and how that applies to the definition of the derivative.  They also will know most of the derivative shortcuts.  And it looks like one of the last topics they will have studied before starting this class is the idea of differentiability.  This topic basically comes at the end of Chapter 4, and BC calculus is supposed to start with chapter 5, which dives into the definite integral.

So before we start with the definite integral though, I want to ease in with some introductory assignments to gently jog their memories of calculus, without the boring beginning of the year review.  Bah!  I also want to establish a classroom culture of discussion and animated participation.  A great activity for the first or second day that I have used in the past involves one student describing a piece-wise graph to her partner that can’t see the graph.  The partner tries to draw the graph from the description, and then later as a class we discuss what sort of vocabulary is helpful and what is not.  I show them them several graphs and they take turns being the describer or the scribe.  I try to pick graphs that have several types of discontinuities so that class discussion leans towards limits and continuity.

I’m always surprised how much students enjoy this activity.  They get really animated in describing their graphs.  Sometimes I have to employ a “sit on your hands” rule so they focus on their vocabulary.  I also have students switch partners  once or twice.  I will definitely be using this again as an introductory activity.

I also found this great video by Numberphile during which Tony DeRose describes some of the math behind Pixar animation.  He talks about parabolas in an animation “meeting in smooth ways” and there are several points where continuity, limits, and differentiability are discussed without him actually using that calculus vocabulary.  I think I will have the students watch the video for homework and then write a paragraph or two about the calculus they might find in the video.  I think it may lead into some good discussions about differentiability.  I’m not sure if I will leave the assignment that general, or if I will give them more specific questions.  I’ll have to think about that over summer break.  Check out the video though.  It’s very interesting.


Well, I was listening to the podcast Strongly Connected Components and heard an interview with the director for the movie Cents.  Here is the trailer.

At the heart of the movie is a classic pre-calculus problem.  Which is worth more;  a penny on day one, and double that amount every day for a month, or a million dollars?  I’m excited to see this movie.  It looks like something my students might enjoy as well.  You can request a screening in your hometown.  See the webpage for Cents for more info.

I haven’t taught pre-calculus in several years, but this doubling problem reminded me of the fun I used to have reading One Grain of Rice: A Mathematical Folktale to my students.  They loved a rare story time in the middle of math class.  I’m sure they would love Cents as well.

Note to self – find some short, fun, calculus readings to share with students.  Any suggestions?


Summer break reading.

It’s summer break, and that means time to read.

First up is Playing with Math by Sue VanHattum.  I have been waiting for this book for so long, and I was very excited when it appeared in my mailbox a little while back.  It did not disappoint.  Lots of inspiring anecdotes, fun games to try, and interesting math problems to share with my students.  One game that caught my attention was Racetrack.  It looks like a neat way to introduce vectors and begin a discussion about velocity and acceleration vectors as well.  It looks like there are some great ideas for math club projects.  There is so much in this book, I know it is one I will go back and read many times.

I’m currently reading  How Not to Be Wrong: The Power of Mathematical Thinking by Jordan Ellenberg.  I’ve heard a lot of good things about this book from many and finally have time to sit down and read.  So far it has been interesting.  I haven’t gotten very far, as I just picked up this book today.  So I will report back later.

And next in my book queue is Really Big Numbers by Richard Evan Schwartz.  This book has a trailer!  This book is aimed at a younger audience, so I am excited to read it with my kids.  Lots of big, bright illustrations and questions that will hopefully appeal to my younger crowd.

So that is what I’m working on this June.

Hello world!

I find I spend a lot of time thinking about math.  I suppose that shouldn’t be too surprising since I teach mathematics for a living.  But recently, I can’t get enough.  I’m reading books, following blogs, and playing with math every chance I get.   So I’m starting this blog as an outlet for sharing this joy of mathematics.