Thursday, August 21, 2008

What's matter?


I start off my physical science class with the usual introductions, procedures and such, but before the first day is over, I tell them that by the end of the year they won't even know what "stuff" is anymore.

"Stuff" is as good a definition of matter as you are going to get at 9th grade, and it's probably as good as you're going to get for most of us without degrees in physics.

The kids look at me quizzically, I gawk back, and away we go!
***

"Stuff" ends up being circular. We can get fancy and call it matter, and the text will tell you that matter is anything with mass that takes up space.

Seems that just about any type of mass a 9th grader is going to run into takes up space, and just about anything that takes up space will have mass.

(OK, OK, bear with me--think about the definitions as presented to our students. Newtonian physics starts with a deceptively simple definition of matter. Teachers fall into the same trap as the students, but if we cannot get the kids curious about what we mean by "stuff", the rest of physics is just a dog and pony show.)

Eventually (months later) we will get to inertia, an operational definition of mass (and again a bit circular), but on the first day of class, the kids are pretty smug about what they know.
OK, Mister Dr. D, matter is "stuff"--we got that, everyone knows what "stuff" is.
So that's it? that's all we gotta know today?
Before I go any further, I tell them that if I do my job, by the end of the year they won't even know what "stuff" is anymore. And more important, they'll know they don't know.

Ah, grasshopper!
***



"So what's mass?"

I'm not looking for a post-doctoral account here, but I don't want to cheat the kids, either.

So I push the issue, even on the first day of class.

If you want someone to learn science, you must first shake them off the ledge of certainty, or rather, convince them they want to jump.
***
OK, so what is it, Mister Dr. D?
I shrug, palms up....Kids don't like it when teachers feign ignorance. They hate it when they realize the teacher isn't faking. A few get mad.
Why we gotta learn this stuff if you don't even know what you're talking about?

I was surprised the first time I saw the anger--I welcome it now.
***

Before the end of the period, I'll review what they know about atoms, or rather, review their misconceptions.

This year I'll show them this model, then take then out to the hall with a grain of sand representing the nucleus of an atom. How far would the electrons roam?

I'll let them walk around. Then tell them to walk farther still.
I must have been in a summer daydream--yes, we'll do the walk-through, but not on day one.

I then tell them that if the nucleus was the size of a grain of sand, then the atom would be the size of a football stadium.

(OK, I haven't done the calculations myself yet, not to mention that I have no clue what the standard football stadium size is. A high school stadium? Giants Stadium? OK, so I need to go back to the chalkboard.)

***

OK, we got two minutes left now, and I need closure. Shoot, I forgot to hand out the texts. Closure...closure...closure.

This is when I need to keep my mouth shut. A good lesson in general.

Now the children are really squirming. The teacher is an idiot, and now he's standing up there speechless. They can't take the pressure.
Uh, that means stuff is mostly space, right?
I smile. And it's nowhere near winter break yet.



6 comments:

Betty said...

I would love to be in your class. At least I am learning about science through your blog.

doyle said...

Thanks for the words.

To be fair, planning for class in August and what actually happens in September can be two very different things.

I was blessed last year--great students. A lot of wackadoodles (I love wackadoodles!) with very few knuckleheads, and even the knuckleheads came around in a month or two.

Clay Burell said...

A propos of nothing other than "this is neat, I think I'll share it with Doyle," you might like this flash timeline of the universe, including evolution of life on earth:

http://www.johnkyrk.com/evolution.html

I was looking for a different one that is, like that photon visual you shared, proportional from the big bang to today. You have to scroll right a ridiculously long time to even see anything happen. It's fun. Can't find it though. Know what I'm talking about?

Ben Wildeboer said...

Excellent! Reminds me when I told them about Schrödinger's cat thought experiment to my physics students. Totally blows their mind and what the perception of reality is all about.

That might be a little too far about freshies heads, but as I'll be teaching freshman science in a new district this year (where they haven't really told me what the curriculum is yet), I may borrow your bit on atoms and the emptiness of everything.

Thanks for the great ideas. I've been enjoying reading your blog very much.

Ben Wildeboer said...

@Clay- I checked out your link. That's one of the better sites of the sort that I've seen. Thanks for passing it on!

doyle said...

Clay,
I have been using John Kyrk for a while, now--he's an amazing person. I had not seen his evolution page, though.

I may use it to introduce biology (with Beethoven's 7th, 2nd movement--I realize for some it's a cliche, but it takes me beyond the herenow).

I love time-lines for perspective, but again, time pressure keeps cutting things short. (We need to have everything done for the "End of the Course" state exam, which is, of course, scheduled a month before the end of the course.)

One more thing--while I tend to revert to Luddism when overwhelmed by folks who confuse tech with knowledge, Kyrk brings me back--he gets it.

Ben,
Thanks for the words--I have taken my "low level" freshman places I thought not possible (though the math's too much of a stretch for most of them, maybe all of them).

Don't tell them it's college level until after you cover it. They shut down when they attempt to assess the difficulty before jumping in (don't we all?).

And I think I'll throw Schrödinger's cat at them this year, just to see what happens.

The nice thing about teaching my freshmen is 1) no end of the year state test, so I can actually teach science, and 2) I pick the low level freshmen as my first choice each year. Administration doesn't have to worry about who's going to teach it, and I get a lot of leeway.