Wednesday, February 16, 2011

Explaining the Scientific Process

One teacher on our Facebook page asked, “Could you explain the scientific process? There seems to be tremendous difficulty for my 3rd graders to grasp it.”

So I went to Dr. William McComas, who holds the Parks Family Endowed Professorship in Science Education at the University of Arkansas. When it comes to the history and philosophy of science in science education, he literally wrote the book. At the heart of "doing science" are questions. Here is what Dr. McComas has to say about explaining and exploring the scientific process for younger students:

Perhaps one reason why some students think that the scientific process is hard to grasp is that they believe that scientific thinking is somehow different from other kinds of normal organized thinking.  Scientists are not any smarter then other folks but they do have curiosity that inspires them enough to spend time and effort to ask questions about the world.
So, scientists start to ask questions that other folks might not have been so curious about.  To answer these questions scientists make observations, do experiments and review the work of others printed in books. They also take notes about what they have discovered and try to put all the information together in a way that makes sense based on the evidence. There isn't any special order to these tasks.  Science use all of these tools to try to answer the question.

Some textbooks include a six or more step process called the scientific method, but scientists don't all use this same step-by-step technique.  Some scientists start to answer the question by going to the library, some start with observations, some start with experiments, some start with hypotheses to guide their thinking and some have a much more open-ended approach.  The steps in the "scientific method" are all useful and used by most scientists at least some of the time, but the scientific process is really just the careful, organized way that scientists look for information to try to answer questions.  The most important thing to know is that anyone can use the scientific process to solve problems as long as they look at all the evidence and make conclusions carefully when there is enough evidence to do so.

Core Nature of Science Ideas to Inform K-12 Science Teaching

The Tools and Products of Science

1)    Science produces, demands and relies on empirical evidence
2)   Knowledge production in science shares many common factors and shared habits of mind, norms, logical thinking and methods such as careful observation and data recording, truth­fulness in reporting, etc. The shared aspects of scientific methodology include the following:
·                Experiments are not the only route to knowledge
·                Science uses both inductive reasoning and hypothetico-deductive testing
·                Scientists make observations and produce inferences
·                There is no single step-wise scientific method by which all science is done
3)    Laws and theories are related but distinct kinds of scientific knowledge. Hypotheses are special, but general kinds of scientific knowledge.
 4)  There are two types of scientific questions.  Questions of the relationship type are "laws" and question of why such relationships exist are "theory type" question.  

Science and the Human Aspects of Science

5)    Science has a creative component
6)    Observations, ideas and conclusions in science are not entirely objective.  This subjective (sometimes called ‘‘theory-laden”) aspect of science plays both positive and negative roles in scientific investigation
7)    Historical, cultural and social influences impact the practice and direction of science

Scientific Knowledge and its Limitations

8)    Science and technology impact each other, but they are not the same
9)    Scientific knowledge is tentative, durable and self-correcting. (This means that science cannot prove anything but scientific conclusions are valuable and long lasting because of the way in which they are developed; errors will be discovered and corrected as standard part of the scientific process)
10) Science and its methods cannot answer all questions. In other words, there are limits on the kinds of questions that can and should be asked within a scientific framework

McComas, W. F. (2008).  Proposals for Core Nature of Science Content in Popular Books on the History and Philosophy of Science: Lessons for Science Education.  In Lee, Y. J. & Tan, A. L. (Eds.) Science education at the nexus of theory and practice. Rotterdam: Sense Publishers.

About Dr. McComas: 
William F. McComas, Ph.D. is the inaugural holder of the Parks Family Endowed Professorship in Science Education at the University of Arkansas following a career as a biology teacher in suburban Philadelphia and professor at the University of Southern California. He is involved in many areas of science education research and policy development. He has served on the boards of directors of the National Science Teachers Association, the International History, Philosophy and Science Teaching Group, the Association for Science Teacher Education (ASTE) and the National Association of Biology Teachers (NABT).  Dr. McComas is widely published in the areas of the history and philosophy of science. He is a recipient of the Outstanding Evolution Educator award from NABT, the Ohaus award for innovations in College Science Teaching and the Outstanding Science Teacher Educator award from ASTE. He is interested in the improvement of laboratory instruction, evolution education, the interaction of the philosophy of science and science teaching, science for gifted students, and science instruction in museums and field sites.    

Tuesday, February 8, 2011

Teaching Physics with Angry Birds: Projectile Motion

I wish Angry Birds had been around when I was teaching high school physics. Please don’t think of the game as a hate crime against hogs, or an avian anger management program—instead, think of it as a computer interactive lab to explore projectile motion and force diagrams. Your students are playing it anyway, at least let them know that they are learning some physics along the way. Launching a bird? No! They are varying the initial angles and velocities to hit a target distance. Take advantage of student interest with the following strategies to help you integrate Angry Birds into your instruction.

            Before Pythagoras (the equation, that is) even comes into the discussion, we should be asking our students to describe projectile motions that they see in their everyday lives. Focus on the big picture question: What are the different factors that determine the range of a projectile? Projectile motion problems can easily become algebra problems that focus on identifying the right number in a diagram and substituting it into the correct equation. We want them to see projectile motion in baseball games, long football throws (think the famous Hail Mary, game-winning touchdown pass by Dallas Cowboys quarterback Roger Staubach to Drew Pearson in a 1975 NFL playoff game), the human cannonball at the circus, rockets, and shooting hoops.

And then there is Angry Birds. The game actually helps your instruction by outlining the bird’s path with dots that are placed at the same time interval, as well as leaving these trajectory paths visible for the next turn. This allows for an overlap and visual comparison of bird trajectories that have different initial angles and velocities. I stress, the goal here is not to try and knock down the structures and take out the pigs, but to use the game platform as a demonstration tool that will get their attention, and to see the flying birds as your projectiles. In a later blog we will look at the structures for teaching force and motion.

Using Angry Birds, you can highlight many of the main points about projectile motion. Things like:
-How do you get a bird to travel the farthest? Answer, 45-degree initial launch angle.
-Can you find multiple launch angles that will land on the same spot? Answer, there are two per spot, and they are complementary angles­.
-What happens when you launch birds at the same angle but change the initial velocity?
-What happens when you launch birds at the same velocity but change the initial angle?
-What launch angles have the longest time in flight? The shortest?

The best levels to use for teaching projectile motion meet these criteria: good open field and no high structures to get in the way of the flight, use of the basic red birds, and having many birds to play with. Theme 1, levels 2 and 3 (see video at the beginning of this blog) offer many birds and a fairly open field for long-range projectiles. Videos of all levels can be found here.

Extra Credit:
In a Wired Science blog, Rhett Allain demonstrates how you can use a simple video tracker program to map the trajectory of the birds in these videos to actually calculate the size of the birds (with the assumption that gravity in the Angry Bird world is also 9.8 m/s^2). You will be surprised at the result—these red birds are BIG!

Teaching molecular polarity and its relation to VSEPR geometries

So I asked teachers on our Facebook page what they would want to know if they could ask a scientist how to explain anything. Our first question was about the concept of molecular polarity and its relation to VSEPR geometries. So I asked Jeff Levy, a teacher who has a Master’s Degree in Chemical Engineering from Carnegie Mellon University and has taught high school chemistry and physics at the Cranbrook Kingswood School in Michigan, the Horace Mann School in NYC and The American School in London about this concept and how he teaches about it. Here is his answer:

 In a nutshell the process goes like this:
1.  Find the molecular geometry using VSEPR theory
2.  Use electronegativity to decide if any bonds are polar
3.  Use the geometry to decide if the polar bond vectors will add or cancel each other out.

VSEPR means this: electrons repel each other (that’s the E and the R) because of the electrostatic force.  This repulsion dictates the arrangement or geometry of atoms within molecules.  When you’re talking about molecular geometry then you only need to consider the bonding pairs and unbonded or “lone” pairs (that’s the P) of electrons that are located in the outer or “valence” shell (that’s the V and S) of each atom.  Valence Shell Electron Pair Repulsion.

When teaching this I always started with gum drops and tooth picks and asked the kids “place X toothpicks in your gumdrop in such a way that all X of your toothpicks point as far away from each other as possible.”  Eventually they come up with the proper geometries (once they start to think in 3D).  I also demonstrated with balloons (tie 4 balloons together at the knot and they naturally form a tetrahedral geometry.)

And then, after you’ve figured out where the atoms are arranged in the molecule, you look at their relative electronegativities and decide where charges will aggregate and if the whole molecule will be polar.

There is a great Molecular Shapes interactive on the Teachers' Domain website,
and a great website that includes many different molecular models that you can rotate and interact with.

Please let us know if you have additional questions!

Tuesday, February 1, 2011

Teachable Moments: Making Stuff Cleaner

Can innovations in materials science help clean up our world? In Making Stuff: Cleaner, host David Pogue explores the rapidly developing science and business of clean energy and examines alternative ways to generate it, store it, and distribute it. Is hydrogen the way to go? What about lithium batteries? Does this solve an energy problem or create a new dependency?

Know: more about smart grids, smartphones, and smart materials.

Do: the Cleaner activity, Build a Cleaner Battery, beginning on page 15 of the Making Stuff Activity Guide (available for free download).