Practice 6 – Constructing Explanations and Designing Solutions

Practice 6 – Constructing Explanations and Designing Solutions


Hi. It’s Paul Andersen and this
is Science and Engineering Practice 6. It’s on constructing explanations and designing
solutions. And so the big theme that this practice is about is about theories. Because
theories are used in science to construct explanations for how the world works. How
the universe and phenomena in it operate. And it’s also used in engineering to design
and test solutions. And so theories are incredibly important but we should talk about what a
theory is. Because if you say I’ve got a theory on who stole my sandwich out the refrigerator,
that’s just a guess. It’s not a theory. How are theories created? Well let’s look through
a flow chart. First of all you come up with an idea. And so maybe we’re looking at the
phenomena of infectious disease. How disease is transmitted from one person to another.
Scientists came up with ideas to explain that. You then preform an experiment and if the
evidence supports the idea you can move one. But if it doesn’t support the idea, no, then
you’ve got a bad idea. So you’ve got to go back again and we have to start all over.
So I have to come up with an idea, design an experiment, test my theory, if it doesn’t
fit, got a bad idea and I start over again. But if it does fit, eventually I could come
up with a theory. And that theory is used to explain phenomena in the universe. It’s
awesome. But it’s developed over a long period of time by scientists and lots of experiments.
But we’re not done yet. What do you do next? Well you discover new evidence. And if that
evidence can be used to modify our theory, to explain the new evidence, then we improve
the theory and we have a better theory. And so the theory gets better and better and better
over time. So we’ve got this feedback loop. But occasionally we’ll come up with new evidence
that can’t modify our theory and so we have something called a scientific revolution.
So we have to start over again and we have come up with a brand new idea. And so theories
are big things in science. They’ve been developed over years and years and years. Let me give
you an example of one. The big bang theory was first proposed by George Lemaitre and
he was a priest but also an astrophysicist, an astronomer and he came up with this idea
of the Big Bang theory. That the universe is like a giant loaf of bread. That all began
at one point and has gotten bigger and bigger and bigger over time. And so we are sitting
within this loaf of bread and we continue to move apart from everything in the universe.
It seems like a crazy idea. Well, evidence started to pile up. Some of the evidence from
Edwin Hubble who was looking into space using a telescope and found that the light every
where in the universe was shifted to the red. What does that mean? It means that everything
in the universe is moving away from us. And if everything is moving away from us then
we could play the time backwards and we get back to a point where the singularity where
everything began. And so evidence has piled up over year after years after years and we’ve
come up with this Big Bang theory. Or maybe the theory of natural selection, which is
sometimes confused, it’s simply an explanation for how species evolve. And so right here
there are two moths. There’s a dark peppered moth and a light peppered moth. And you might
say, “Well, wow. This one blends in perfectly. Wonderful camouflage.” Well scientists tried
to come up with an idea of how they could evolve to a climate. Some people thought they just were created that way. One of the first ideas was the idea somehow purposed
by Lamarck that they can somehow will themselves to change. So for an example a giraffe got
a long neck by stretching up to reach leaves higher in the tree. They didn’t understand
how genetics worked and how information was passed from generation to generation. And
eventually Charles Darwin came up with this theory of natural selection. You have variation
in a population. So you have moths that are dark and moths that are light and then the
ones that don’t fit in are selected. In other words they’re eaten by birds. And so over
time species are going to start to adapt to their local climate. So there was argument
about this. And over next fifty years it became established as the scientific theory. And
we really haven’t changed it much since the time of Darwin to explain how evolution occurs.
Let me give you another one you maybe never heard of. It’s called the Miasma Theory. This
was a theory that explained infectious disease. The idea went like this, that organic material,
when it dies, give off this bad air or this miasma that moves through. So this is an explanation
for how typhoid fever would spread throughout people. And this is a book on the prevention
against bad air. Well science didn’t stack up to support the Miasma Theory and so it
was thrown out and replaced by the Germ Theory. Scientists like Louis Pasteur, and this is
his pasteur flask, started to study, well, how does something go bad? How does something
spoil? And at this time we were also using microscopes to look at microscopic life. And
so eventually we came up with this germ theory. That bacteria and viruses are passed from
one organism to another that cause disease. And evidence started to pile up and now we
have the germ theory. But it could eventually be replaced by something else. And so when
we’re talking about a theory it’s well established. Well in the science classroom then what is
a hypothesis? It’s not a scientific theory. And it’s not like a lot of teachers will say,
it’s not an educated guess. What is a hypothesis? A hypothesis is a plausible explanation for
what we are seeing or our observations. And so it’s not just a wild guess. It’s an explanation
of what we think is going on. And this works best through analogy. So basically we sit
here with all of these scientific theories and then we make new observations. And those
observations we can bridge the gap between theories and observations using explanations.
Using hypothesis or hypothesis testing. Now in engineering it’s a little bit different.
They also come up with guesses and explanations, but they use that as a part of what’s called
the cycle of design. So basically you start by planning. So you come up with a problem
or a human need that we have to fulfill. You then design a solution to that. You create
the solution and then you evaluate it. And then after you’ve evaluated it, then we may improve
upon a new design, a better design. We create that. Test it and then we do that same thing
over and over again. So there still is this idea of me explaining what happened, what
went wrong, what went right. Here’s an example. So this is the first apple computer. Basically
it just shipped you the motherboard and you had to build everything around the outside
of it. That was improved by the Apple II. That was my first computer. And then the MacIntosh,
the IMac and now the IMac that we have today was created through design and the cycle of
design getting better and better and better over time. But it starts with an explanation
of first define the problem. What do we have to solve? And then let’s solve it. And so
the goal in science education is to have our students constructing explanations and then
designing solutions. And so what’s a nice progression for that? In other words, if we
think of the analogy of a bulls eye, we want our students from day one in elementary school
throwing darts at this board, constructing explanations. And then over the years we want
them to get better and better and better and better. Closer to the bulls eye. So the framework
suggests owl pellets as a good way to get started in elementary. So basically you order
these owl pellets. These are from a long eared owl. Student’s break it apart. They get the
bones out of it . They use a sheet to figure out what rodents are in there and then they’re
trying to construct an explanation. So what are they trying to come up with? What do these
owls eat? What does their diet consist of? You want students making guesses really early
in their education. Or we could give them plant growth for example. So students could
be growing plants in school. They could make guesses as to what could increase plant growth.
So they might come up with the idea of sunlight, so they need a certain amount of light. And
so you could increase the amount of light and see how that affects plants. But maybe
you don’t water them and they die as a result of that. Well now this is a new explanation
so we have to get better and better and better. You want students making guesses and you can
do that individually or as a class. As you move into middle school the problems can be
harder but the explanations are very important. So an example, this is one I ask my students
all the time, why does boiling water bubble? Like, where are the bubbles coming from? And
a really common guess is that it’s hydrogen and oxygen gas, because we know that there’s
H2O. That would be scary if you had hydrogen and oxygen gas coming out of boiling water
because they’re both, I mean it’s hugely explosive. So it’s not that. So you want them making
guesses and then modifying those guesses to fit with the established theories that we
have. It’s also important that they start designing solutions. And so you can do this
in elementary. Like bridge building are great competitions that you can do. Where we can
test out different designs. And that can move all the way up through high school and big
designs. Like this is a solar car competition and obviously you can’t do that in a classroom,
but it’s something your school should be working on. And we could do this, like this is something
I do in my class. We do water quality testing where we’re looking at the quality of the
water in the creek that just goes right outside of our school. But we can also build upon
that. How can we make it cleaner? How can we clean up the water in this creek? And so
designing solutions are important. We want students doing it from day one, but the sky’s
the limit. In high school we can do incredible projects. We can make the world a better place
and I hope that’s helpful.


9 thoughts on “Practice 6 – Constructing Explanations and Designing Solutions

  1. "Crik"……haven't heard that word said like that forever, cute! Love your videos; use them lots to train our foreign teacher staff here in Thailand

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