Hi. It's Paul Andersen and this is Crosscutting Concept 6. It's on structure
and function. In other words how the structure of an object fits its function or its job.
How the form fits the function. So if I were to look at my hand, my hand has a specific
structure. It's got a number of four fingers. One thumb. They articulate in a specific way.
But the length of them and the way they articulate are all going to fit their function. They
allow me to write. They allow me to draw. And they allow me to type. And so this cuts
across all of the sciences. The life sciences, the earth sciences, and the physical sciences.
My hand and a robot arm are going to have specific structures and they're going to allow
them to do a job. And this is fun. Once you start looking at the structure and how it
fits the function it opens up a whole world of science and engineering. And so we tend
to take this for granted. And so this is a great activity that you could try in your
class. Give somebody a piece of paper, and you can try it right now. And without looking
at anything or asking for help or asking you what parts or part of it, draw a picture of
a bicycle. And so this website by Rebecca Lawson kind of gets at this. That we really
understand how to ride a bicycle, most of us. But we have no idea how it actually works.
And so let's take a quick quiz on the science of "cycology". And so if we were to look at
the bicycle frame, choose one of these four letters. Which of theme most looks like a
bicycle frame? So if this is the seat and these are the handlebars, quickly lock in
your answers. Is it A, B, C or D? Now let's look at the pedal placement. Is it in the
middle? Is it at the top? Is it going to be at the back wheel? Or at the front wheel?
And now let's look at the chain and the position of the chain. Is the chain going to be here
as in A? Here as in B? Here as in C? Or here as in D? And so hopefully you've locked in
those three guesses on frame, pedal and chain. And now let's look at the right answers. Right
answer is going to be this. Now this is easy for me to get. And that's because I like bicycles.
I ride a bicycle to work and I really understand how they work. So this would be the frame.
C should have been the right answer. The pedals are right in the middle. And the chain just
goes around from the pedal back to the back wheel. And you might say wow, this is really
easy. But I promise you if you give this to your students, give them a sheet of paper.
Don't let them cheat, they're going to do horribly at it. A lot of them are not going
to do that well. And that's because lots of times we don't understand how what we're using,
its structure fits its function. And that's what this concept is about. It's important
to understand this because in science it allows us to better understand phenomena. And engineering,
we can understand how design works and then hopefully improve the design. And so the first
step is really understanding what's going on. And so let's use those two terms. So what
is the structure? Structure is what it's made up of. And so in this crescent wrench here,
the wrench itself is going to be it's structure. And so it's going to be long right. It's going
to be really, really hard and stable. This part is going to articulate and so you're
going to turn this and then it's going to move this spanning position over here. So
we actually call a crescent wrench an adjustable spanner. And so now I've described the structure,
but this is the function. So why is this really really long? It's so you can generate a huge
amount of leverage on the end if you're trying to work on a specific bolt. And why is this
articulate in this direction? This would actually be a simple machine. Right here we've got
a wedge, and that wedge is working as a, with an axel to actually move this. And so we get
a huge amount of force that we can generate on this side. And so the structure is fitting
the function. And really if you start looking at it again, it opens up the world. And so
this is a bicycle. And so if we look on a bicycle itself there's going to be so many
different structures on it. And so we're going to have gears, a chain. We're going to have
levers up here on the brakes. We're going to have cables and pulleys. And all of the
form of the bicycle fits its specific job or specific function. But I could've, instead
of throwing up a bicycle, I could have thrown up a human skeleton. And it's going to have
similar structures. And those structures are fitting the functions. Now one thing that
you should work with your students on is the idea of scale. That certain structures are
going to be important at this scale, so a lot of simple machines. But if we were to
zoom into the aluminum inside this frame, now the atomic structure is going to fit the
function. And so depending on our scale, be it very very small at the microscopic level
or very very large, we're going to have to start looking at different structures to see
how those effect specific functions. And so what's the goal with this concept? We want
students to understand structure and function. How do you teach this? What's the progression?
Well in the early elementary grades we want them looking at mechanical function and then
moving into complex systems as they move through the elementary grades. As they get into middle
school we can start talking about molecular structure. And then finally when they're in
high school, we can investigate phenomena. We can apply these ideas of structure and
function to understand how real complex systems work. And so where to begin with, in other
words what's the progression? How do you get students in your early elementary grades looking
at structure and function? Well one of the ways to do that is start using those terms.
And so if we were to look at this bridge, and you could even do a bridge building activity,
there's going to be certain structures that are going to do better and certain that aren't.
And so one structure that I pick right away is the triangles. The triangles are going
to be repeated over and over. And we even have triangles within triangles within triangles.
And so why do we have that? Well triangles are inherently stable. And so the structure
of a triangle makes it hard to compress. If this were to be, triangles are great, but
if these were to be squares it's easy for a square bridge to just kind of flex underneath
it. Good ways to kind of get at this is have kids build. And so my favorite challenge to
start the year with is called the marshmallow challenge. There's a wonderful Ted Talk on
this. But basically you're giving some limited things. So you get some spaghetti, I think
20 strands of spaghetti, a marshmallow, some string, tape. And what you have to do is to
build a structure, a free standing structure that can be as tall as you can make it. And
then you give them a specific time. I think 20 minutes to do this. And there's directions
online. And so what you do is you give your kids a challenge and then they have to build
a structure. And that structure has a specific function. In this case it's to hold the marshmallow
up. One quick thing that's worth noting is that kindergarten students tend to do better
than older kids at this. Because they put their marshmallow on right away and so they
iterate. They try different ones over and over and over time. And when I do this in
my class lots of times they'll wait until the end before they actually put the marshmallow
on and then the whole thing folds on itself. As we move in to the upper elementary grades
we should start looking at complex systems. And so like a skeleton and the skeletal system.
I had mentioned before its specific structure is going to be tied to the function, to the
job that it does. As we move in for example to the respiratory system the structure of
the lungs, there's a number of structures we could talk about. So it's increase surface
area. I think the surface area of your lungs is something about the same size of the surface
area of a tennis court. And so why do we need a great surface area inside the respiratory
system? So we can start talking about complex systems inside our body. And we could even
talk about complex systems on the earth. And so understanding how plate tectonics work,
how plates are moving around. Once we understand how that works we can make predictions about
what's going to happen when those plates come together. As we move then into middle school
we should start looking at molecular structure. And so water molecules are going to have a
specific shape. They're going to have the oxygen in the middle and hydrogen on the side.
But they'e also going to have different charges. So they're going to have negative charges
down here and then positive charges up where the hydrogen is. And so what that gives us
is something called a hydrogen bond. So the structure gives us the function of the bond,
but that can lead to understanding how water works. And ice works. And so in this picture
right here we have liquid water. Solid water. Ice. And then we also have water vapor which
you can't see. I mean the clouds are going to be liquid water that's condensed. And so
even in the air we have water that you can't see. And the structure of the water molecules
is important in understanding how these all work. Water's something that's incredibly
unique it that it floats when it becomes a solid. It is actually less dense then when
it's a liquid. And most things don't do that. And it's hard to understand how that works
unless you have intimate knowledge of how the molecular structure works. And then finally
as we move into high school we want to get more complex in those models and we start
to try to investigate phenomena and understand how they work. And so this right here is the
lac operon. And you don't really need to know what that means. It's basically a way that
bacteria can regulate the amount of lactose inside them. And so when you're looking at
something like this. So if we're looking at a model, first thing you want to do is identify
the parts. You then want to identify the different shapes. And then you want to identify how
the shape fits the function. How the structure fits the function. So if I were to run this
animation right here, somethings you could start to figure out right away is that we've
got a little DNA down here. This molecule, its specific shape is going to fit right there
on that. And when it does, it doesn't allow this RNA polymerase to move forward. And so
this is a phet simulation. I'll put a website down below and I find that if I can throw
those up on the board in the front of the room, kids can start to understand the structure
and how that fits the function. And then we can kind of work backwards from that. And
then we can get to the content. And so again. Form fits function and I hope that was helpful.