October 2011: Forgetting Things in Math Class




Uploaded by MDWeathers on 12.11.2011

Transcript:
We can do trigonometry with really large triangles, too.
If I draw a point there,
another point over here,
and I make an angle of forty seven degrees,
and then I draw a point way up here,
that's a really large triangle.
Hey wait a second, what's going on here?
Is it that time of year again?
Well, as I was saying, you can do trigonometry with really large triangles.
Actually, that's what the Greeks did,
using trigonometry and geometry to discover the size of the earth -
they knew the earth was a sphere -
and to discover the distance to the moon
and the distance to the sun.
Isn't it interesting the humanity forgot about that
for several centuries after that.
That's what I want to talk about today: how easy it is for us to forget things.
For example, I just wrote an angle over there,
just thirty seconds ago, but do any of you
remember what number I wrote over there?
Here's another example.
Due to a phenomenon called inattentional blindness,
things that we're not paying attention to
we don't really see.
For example, what color of shirt am I wearing
behind this screen?
I was standing in front of you teaching class
for the whole class period
but did you actually see what color I was wearing?
>> Nope.
>>So, was I wearing a red shirt?
Or, maybe I was wearing an orange shirt.
Or, maybe I was wearing a green shirt.
[laughter]
Thank you, that's quite enough.
>> But I want them to see my nice green shirt
>> I think they get the picture
You can leave now, go on, get out of here.
>> Okay, fine.
>> Okay, so what color of shirt am I wearing behind this screen?
Am I wearing a red shirt, or an orange shirt
or a green shirt?
Well, I could just tell you,
but instead of telling you, I'll just show you.
So here's what color of shirt I'm wearing.
[laughter]
>> How many of you got it?
Most of you did
Hey, what's he doing here?
Hey, what are you doing here? Go on, get out of here.
>> Well, I want them to see
my nice green shirt again
>> No, the trick is over, we're done, get out of here.
>> Okay. Hey, did you ask them about the pumpkin?
>> About the pumpkin? What?
>> Did you ask if they noticed the pumpkin moving earlier?
I'll show you a replay
[laughter]
[applause]