< Return to Video

Doodling in Math Class: Spirals, Fibonacci, and Being a Plant [1 of 3]

  • 0:00 - 0:02
    Say you're me and you're in Math class
  • 0:02 - 0:03
    and your teacher's talking about-
  • 0:03 - 0:05
    Well, who knows what your teacher's talking about.
  • 0:05 - 0:06
    Probably a good time to start doodling
  • 0:06 - 0:08
    and you're feeling spirally today, so, yeah.
  • 0:08 - 0:10
    Oh, and because of over-cutting in your school
  • 0:10 - 0:12
    your Math class is taking place in Greenhouse #3:
  • 0:12 - 0:13
    Plants!
  • 0:13 - 0:16
    Anyway, you've decided there are three basic types of spirals.
  • 0:16 - 0:18
    There's a kind where as you spiral out,
  • 0:18 - 0:20
    you keep the same distance, or you could start big
  • 0:20 - 0:21
    and make it tighter and tighter as you go around,
  • 0:21 - 0:23
    in which case the spiral ends,
  • 0:23 - 0:25
    or, you could start tight but make it bigger as you go out.
  • 0:25 - 0:27
    The first kind is good
  • 0:27 - 0:28
    if you really want to fill up a page with lines
  • 0:28 - 0:30
    or if you want to draw curled up snakes.
  • 0:30 - 0:32
    You can start with a wonky shape to spiral around.
  • 0:32 - 0:33
    But you've noticed that, as you spiral out,
  • 0:33 - 0:35
    it gets rounder and rounder,
  • 0:35 - 0:36
    probably something to do with
  • 0:36 - 0:38
    how the ratio between 2 different numbers approaches 1
  • 0:38 - 0:39
    as you repeatedly add the same number to both.
  • 0:39 - 0:42
    But you can bring the wonk back by exaggarating the bumps
  • 0:42 - 0:44
    and it gets all optical illusiony.
  • 0:44 - 0:46
    Anyway, you're not sure what the 2nd type of spiral's good for
  • 0:46 - 0:49
    but it's a good way to draw snuggled up Slug Cats
  • 0:49 - 0:50
    which are species you've invented
  • 0:50 - 0:53
    just to keep this spiral from feeling useless.
  • 0:53 - 0:56
    This 3rd spiral, however, is good for all sorts of things.
  • 0:56 - 0:57
    You could draw a snail or a Nautilus shell,
  • 0:57 - 0:59
    an elephant with a curled up trunk,
  • 0:59 - 1:01
    the horns of a sheep, a fern frond,
  • 1:01 - 1:04
    a cochlea in an inner ear diagram, an ear itself.
  • 1:04 - 1:05
    Those other spirals can't help
  • 1:05 - 1:08
    but be jealous of this clearly superior kind of spiral.
  • 1:08 - 1:09
    Better draw more Slug Cats.
  • 1:09 - 1:11
    Here's one way to draw a really perfect spiral:
  • 1:11 - 1:14
    Start with 1 square, and draw another next to it
  • 1:14 - 1:15
    that is the same height.
  • 1:15 - 1:17
    Make the next square fit next to both together.
  • 1:17 - 1:19
    That is, each side is length 2;
  • 1:19 - 1:21
    The next square has length 3.
  • 1:21 - 1:23
    The entire outside shape will always be a rectangle.
  • 1:23 - 1:26
    Keep spiralling around, adding bigger and bigger squares.
  • 1:26 - 1:32
    This one has side length 1,2,3,... 12,13, and now 21.
  • 1:32 - 1:33
    Once you do that, you can add a curve
  • 1:33 - 1:35
    going through each square, arcing from one corner
  • 1:35 - 1:38
    to the opposite corner. Resist the urge to zip quickly
  • 1:38 - 1:41
    across the diagonal if you want a nice, smooth spiral.
  • 1:41 - 1:43
    Have you ever looked at the spirally pattern on a pinecone
  • 1:43 - 1:45
    and thought 'hey, sure are spirals on this pinecone'?
  • 1:45 - 1:47
    I don't know why there're pinecones in your Greenhouse.
  • 1:47 - 1:49
    Maybe the Greenhouse is in a forest.
  • 1:49 - 1:51
    Anyway, there're spirals, and there's not just one either.
  • 1:51 - 1:54
    There are 1,2,3,...8 going this way,
  • 1:54 - 1:55
    or you could look at the spirals going the other way,
  • 1:55 - 1:59
    and there are 1,2,3,...12,13.
  • 1:59 - 2:00
    Look familiar?
  • 2:00 - 2:03
    8 and 13 are both numbers in the Fibonacci Series.
  • 2:03 - 2:05
    That's the one where you start by adding 1 and 1 to get 2
  • 2:05 - 2:07
    and 1 and 2 to get 3, 2 and 3 to get 5,
  • 2:07 - 2:11
    3+5=8, 5+8=13, and so on.
  • 2:11 - 2:14
    Some people think that instead of starting with 1+1
  • 2:14 - 2:19
    you should start with 0 and 1; 0+1=1, 1+1=2, 1+2=3,
  • 2:19 - 2:21
    and it continues on the same way as starting with 1+1
  • 2:21 - 2:24
    or I guess you could start with 1+0,
  • 2:24 - 2:25
    and that would work too
  • 2:25 - 2:27
    or why not go back one more to -1, and so on.
  • 2:27 - 2:29
    Anyway, if you're into the Fibonacci Series
  • 2:29 - 2:31
    you probably have a bunch memorized.
  • 2:31 - 2:33
    I mean you've got to know 1,1,2,3,5,
  • 2:33 - 2:35
    finish off the single digits with 8
  • 2:35 - 2:37
    and oh, 13, how spooky!
  • 2:37 - 2:38
    And once you're memorizing double digits,
  • 2:38 - 2:41
    you might at well know 21,34,55,89,
  • 2:41 - 2:42
    so that whenever someone turns a Fibonacci number,
  • 2:42 - 2:44
    you can say 'Happy Fibirthday!'
  • 2:44 - 2:48
    And then, isn't it interesting that 144,233,377?
  • 2:48 - 2:51
    But 610 breaks that pattern,
  • 2:51 - 2:52
    so you'd better know that one too...
  • 2:52 - 2:54
    And oh my goodness, 987 is a neat number!
  • 2:54 - 2:56
    And, well, you see how these things get out of hand.
  • 2:56 - 2:58
    Anyway, 'tis the season for decorative, scented pinecones.
  • 2:58 - 3:00
    and if you're putting glitter glue spirals
  • 3:00 - 3:02
    on your pinecones, uh, during Math class,
  • 3:02 - 3:04
    you might notice the number of spirals are 5 and 8,
  • 3:04 - 3:08
    or 3 and 5, 3 and 5 again, 5 and 8.
  • 3:08 - 3:09
    This one was 8 and 13
  • 3:09 - 3:11
    and one Fibonacci pinecone is one thing,
  • 3:11 - 3:14
    but all of them? What is up with that?
  • 3:14 - 3:15
    This pinecone has this wumpy, weird part.
  • 3:15 - 3:17
    Maybe that messes it up. Let's count the top.
  • 3:17 - 3:20
    5 and 8, now let's check out the bottom: 8 and 13.
  • 3:20 - 3:23
    If you wanted to draw a mathematically realistic pinecone,
  • 3:23 - 3:25
    you might start by drawing 5 spirals one way,
  • 3:25 - 3:27
    and 8 going the other. I'm going to mark out
  • 3:27 - 3:29
    starting and ending points for my spirals first
  • 3:29 - 3:31
    as a guide, and then draw the arms,
  • 3:31 - 3:32
    8 one way, and 5 the other.
  • 3:32 - 3:35
    Now I can fill in the little pineconey things.
  • 3:35 - 3:37
    So there's Fibonacci numbers in pinecones,
  • 3:37 - 3:38
    but are there Fibonacci numbers
  • 3:38 - 3:39
    in other things that start with 'pine'?
  • 3:39 - 3:41
    Let's count the spirals on this thing.
  • 3:41 - 3:47
    1,2,3,... 8, and 1,2,3,... 13.
  • 3:47 - 3:49
    The leaves are hard to keep track of,
  • 3:49 - 3:51
    but they're in spirals too, of Fibonacci numbers.
  • 3:51 - 3:53
    What if we look at these really tight spirals
  • 3:53 - 3:54
    going almost straight up?
  • 3:54 - 4:01
    1,2,3,....21! A Fibonacci number.
  • 4:01 - 4:03
    Can we find a third spiral on this pinecone? Sure!
  • 4:03 - 4:05
    Go down like this, and...
  • 4:05 - 4:10
    1,2,3,.... 21!
  • 4:10 - 4:12
    But that's only a couple examples.
  • 4:12 - 4:13
    How about this thing I found on the side of the road?
  • 4:13 - 4:16
    I don't know what it is, it probably starts with 'pine' though.
  • 4:16 - 4:19
    5 and 8. Let's see how far the conspiracy goes.
  • 4:19 - 4:21
    What else has spirals in it? This artichoke has 5 and 8.
  • 4:21 - 4:23
    So does this artichoke-looking flower thing,
  • 4:23 - 4:25
    and this cactus fruit does too.
  • 4:25 - 4:27
    Here's an orange cauliflower with 5 and 8,
  • 4:27 - 4:29
    and a green one with 5 and 8. I mean, 5 and 8.
  • 4:29 - 4:31
    Oh, it's actually 5 and 8.
  • 4:31 - 4:33
    Maybe plants just like these numbers though,
  • 4:33 - 4:35
    doesn't mean it has anything to do with Fibonacci,
  • 4:35 - 4:36
    does it?
  • 4:36 - 4:37
    So let's go for some higher numbers.
  • 4:37 - 4:39
    We're going to need some flowers.
  • 4:39 - 4:41
    I think this is a flower, it's got 13 and 21.
  • 4:41 - 4:43
    These daisies are hard to count, but they have 21 and 34.
  • 4:43 - 4:45
    Now let's bring in the big guns.
  • 4:45 - 4:55
    1,2,3,4,......34!
  • 4:55 - 5:03
    And 1,2,3,4,5,........ 55!
  • 5:03 - 5:04
    I promise this is a random flower
  • 5:04 - 5:06
    and I didn't pick it out especially to trick you into thinking
  • 5:06 - 5:08
    that there're Fibonacci numbers in things.
  • 5:08 - 5:10
    But you should really count for yourself
  • 5:10 - 5:11
    next time you see something spirally.
  • 5:11 - 5:13
    There're even Fibonacci numbers
  • 5:13 - 5:15
    in how the leaves are arranged on this stalk,
  • 5:15 - 5:16
    or this one,
  • 5:16 - 5:18
    or the brussel sprouts on this stalk
  • 5:18 - 5:19
    are a beautiful, delicious 3 and 5.
  • 5:19 - 5:22
    Fibonacci is even in the arrangement of the petals on this rose,
  • 5:22 - 5:26
    and sunflowers have shown Fibonacci numbers as high as 144.
  • 5:26 - 5:28
    It seems pretty cosmic and wondrous,
  • 5:28 - 5:30
    but the cool thing about the Fibonacci series and spiral
  • 5:30 - 5:32
    is not that it is this big, complicated,
  • 5:32 - 5:34
    mystical, magical super-Math thing,
  • 5:34 - 5:36
    beyond the comprehension of our puny human minds
  • 5:36 - 5:38
    that shows up mysteriously everywhere.
  • 5:38 - 5:40
    We'll find that these numbers aren't weird at all.
  • 5:40 - 5:42
    In fact, it would be weird if they weren't there.
  • 5:42 - 5:44
    The cool thing about it is
  • 5:44 - 5:46
    that these incredibly intricate patterns
  • 5:46 - 5:55
    can result from utterly simple beginnings.
Title:
Doodling in Math Class: Spirals, Fibonacci, and Being a Plant [1 of 3]
Description:

Part 2: http://youtu.be/lOIP_Z_-0Hs
Part 3: http://youtu.be/14-NdQwKz9w
Re: Pineapple under the Sea: http://youtu.be/gBxeju8dMho

more » « less
Video Language:
English
Duration:
05:55

English, British subtitles

Revisions