# A stupidly simple mnemonic for acceleration graphs

When working with position/time graphs of accelerated motion, it is easy to confuse the dire
ction of velocity with the direction of acceleration. for example, look at the two graphs below:

Many students will instinctively say that the first graph is positive acceleration, while the second graph is negative. In fact, these are the same graph, as you can see here:

It is a single parabola, representing positive acceleration.

So how do I get kids to recognize positive and negative acceleration? Using the following, stupidly simple trick:

Positive face

Negative face

It’s really that simple. Any part part of the smile, be it a corner of the mouth smirk or a full on grin, still looks positive. Any part of the frown still looks negative. And that’s it.

# Optics Song

One of my students started this off, and we just had to finish it. Sung to the tune of Frère Jacques:

Denser slower, Denser slower
That’s how light, That’s how light
Undergoes refraction, Undergoes refraction
That’s Snel’s law, That’s Snel’s law

(Note that while it is usually referred to as Snell’s Law, the person for whom it is named was Willebrord Snel, with one “l”. He later went by the latinized “Snellius”, but it is not called Snellius’ Law, so I will be pedantic and stick with Snel’s Law.)

# More on non-drooling autotrophs

My earlier post “Autotrophs don’t actually drool“, which references the Big Bang Theory song, is one that gets some of the most hits on this site. Go figure. Apparently lots of people are doing searches for drooling autotrophs. But since that post doesn’t actually explain what autotrophs are, I think those people are going away disappointed. So here’s the skinny:

“Troph” refers to eating. Autotrophs produce their own food (through photosynthesis or chemosynthesis), while heterotrophs consume other things (herbivores, carnivores, detritivores, decomposers). Drooling involves a mouth. Autotrophs, since they produce their own food, don’t have mouths, and don’t drool. (And to pre-empt those who would trot out Euglena as both an autotroph and a heterotroph, and therefore does eat, I will point out that it does so through phagocytosis. It doesn’t have a mouth.)

# Microscope Diagram

Many years ago, as a (fairly) new teacher, I made a diagram of a typical microscope that I was rather proud of. The years went by, and my photocopied versions would run low, so I would copy the copies, but the original seemed to have vanished. Well, today while looking for something else, I came across the original. So to celebrate, I am sharing my humble little microscope diagram with the world at large. Enjoy!

# If you want something done…

There is an old adage:

If you want something done, give it to a busy person.

Which is kind of the flipside of:

A job expands to fill the time available.

I currently find this to be very true, because, well, it’s summer. Of all the things I had planned, I have only accomplished a few, because, well, there’s no time left after I have my coffee, read the latest blog posts, check my email, write a little, have some lunch, and WHOA where did the time go?

So I’m setting out some things that have to get done, a so-called “honey-do” list. That helps.

But it also gets me thinking about student workload. Perennially, we hear from students, from parents, and even some well-intentioned faculty or admin that seniors need some breaks in the day so they can keep on top of their work, in order to get the best possible marks for university. Yet it seems to be that it is the busy students with heavy workloads who do better academically. Of course, I haven’t controlled for cause and effect – are more motivated and academically inclined students the ones who opt to take more courses, or is it that taking fewer courses creates a more relaxed, summer attitude that leads to less diligence. Probably a combination of both.

Many things in life are counter-intuitive, and this is one – though one we have probably all experienced. We want the best for our students, and sometimes that means pushing them toward being a busy person so they can get more done.

Now I have to start building a deck before it’s time for lunch.

# Status update

So, there appears to be an issue migrating this site to the new host, and they seem to be in no great hurry to fix it. While I wait patiently (and send them almost daily requests for updates), I am reluctant to add too much in the way of new content. So please, dear reader, be patient.

# more milestones

If you look way, way down at the bottom of the page you will see a tiny hit counter. That counter just cracked the 1000 barrier.

Thank you for visiting, I hope you will return!

# Student quotes

Sometimes my students say the greatest things – insightful, funny, or just plain poetic. Here are a few quotes from this year:

Zero is just a place – jk

Yup, pretty much.

I will never trust any data ever again – jk

Good. Just because it’s there, doesn’t mean it’s right. Be critical when examining everything.

The Alchemists tried to use Aristotle’s theory to create the impossible. – mn

This from a discussion of the history of atomic theory. One wonders if Aristotle had lost the argument, if we would have had advanced chemistry by the time of the Roman empire.

“If you add the word ‘quantum’ in front of anything, you sound smart. Like, ‘Quantum Water Bottle'”
-NG & AN

Oh, so true. Now where did I put my quantum coffee cup?

“Wow, it’s even in COLOUR” – NH

This was pronounced when we were looking at a real image projected onto paper by a concave mirror. I think I laughed for five minutes straight. Though, to be fair, she had computer science right before AP Physics, and had been working on how computers portray colour. But still a good giggle.

# Sarcasm

Sometimes, just sometimes, I really want to say something like this:

You know you want to too. Not that I would ever use or endorse the use of sarcasm in class (no, honestly, that isn’t sarcasm). But is it a crime, once in a while, when it is really deserved, to think it?

# We live in wondrous times

The fact that every student has at their disposal at least one method for recording images, audio and video at any given time is really quite astounding. Between cell phones, iPods with video, and the webcams on their computers, students are able to record experimental observations and results for later verification, and to share with each other. I use my own iPod nano (the previous generation, which my students now find quaint..) to make video recordings of demos and so on to post online for my students. And some of the students even have actual cameras. You know, that don’t have phones in them.

Just a few short years ago none of this would have been possible. We really do live in wondrous times!