Wednesday, October 3, 2012

How does the Science Posse interact with k-12 students?

Recently we were asked How does the Science Posse interact with k-12 students? In particular, what if a Wyoming student is exclusively home-schooled? Do they still have access to Science Posse resources?

Answer from Posse Coordinator Megan Candelaria:

Great question!! We interact with students both during our two science summer camps and also through our school-year activities. Any teacher in the state of Wyoming can request us through our online request form (found at our webpage: Our graduate students - who are masters and PhD candidates in STEM fields - will then work with that teacher to bring students interactive, hands-on STEM activities. Here are a few of the options we offer:

• Lab Tours: graduate fellows bring middle and high school students into their research labs at the University, providing a hands-on experience of what scientists, engineers, and mathematicians do.

• Science Mini-Lessons: graduate fellows engage students with short, interactive, enjoyable hands-on activities that tap into the ‘wow’ factor of math, science, and engineering!

• Specialized Lessons: teachers’ request graduate fellows in the fellow’s area of expertise to have the fellow design specialized lessons to meet the curricular needs of the classroom with a hands-on, innovative activity.

• Focus on Mathematics: The Science Posse's mathematicians will bring hands-on, inquiry based mathematics lessons incorporating our research to your students!

• We also provide science fair mentoring, consulting, and judging.

You can learn all about what we do, view our current graduate students (and see their areas of expertise), see examples of past and current lesson plans, as well as fill out a request form on our website. (Requests for fall 2012 will open September 1st.) All of our services are completely free to schools as we are funded by an NSF GK-12 grant as well as the University of Wyoming. Our current grant has a focus on middle and high school students, however we also work with elementary schools.

We love sharing our passion for science, mathematics, and engineering with Wyoming students!

Homeschooled students can (and often do!) attend our summer camps, which are week-long adventures in science, mathematics, engineering, and place-based education. We also have worked with homeschool groups in the past when a parent or guardian has gotten a group of home schooled students in the community together and provided an appropriate space for an activity to occur. Homeschool students would also be more than welcome to come to campus for lab tours. The Science Posse works with many programs throughout the state besides the 'traditional' classroom, from Big Brothers Big Sisters here in Laramie to the Wyoming Boys' School in Worland. If traveling to you or you traveling to us is not an option, we also have the capability to do 'virtual visits' using a program called Blackboard Collaborate. All cyber set-up is done on our end; all that is needed on the other end is an internet connection, microphone, and a webcam!

Tuesday, September 18, 2012

Can I build and EMP?

Recently a Wyoming sophomore asked us, "I'm looking into building a small scale EMP for the Science Fair. Do you think this would be okay with ISEF?"

Several of the Science Posse's engineering graduate Fellows responded:

What an interesting idea!

Unfortunately, there is a pretty good chance that playing around with an ‘electromagnetic pulse’ producer immediately rubs up against FCC rules in the US Because the effects of EMP can be damaging to both electronics and people (and other living things), I'd back away from it pretty quickly.  A "twist" on the idea might be to look at EM sensing, that is, there are a bunch of things that can be "picked up in the ether," beyond just radio broadcasts.  Here's an example detector found via googling:

Wednesday, September 5, 2012

Slippery Science!

Recently a Wyoming sophomore asked us, "I am currently considering researching and doing my project on the coefficient of friction and how it applies to winter sports. I heard that when you snowboard down a hill, the friction between the board and the snow melts a thin layer of it and gives you a sheet of water to slide on. I am looking to research this more in depth and possibly experiment with different amounts of friction."

Wow!  What an interesting project!  One of our graduate students in mathematics, Stephen Garth, found an article he thought might be interesting to you as it looks at the same idea you are interested in, although it talks about the idea using ice skating. We would encourage you to read it over and then get back to us with how that might impact what you want to research, and how you might research it.  (What does the article say about the ice melting under an ice skate? Do you think the same might be true with a snowboard?)   From there, we can try and match you up with a mentor who could help you a bit more!

Here is the link to the article that talks about 'why ice is slippery':  The New York Times article is pretty good and also nontechnical.  

Also Cornell has an “Ask a Scientist” portion on their Center for Materials Research website which is also below. This might be another great resource for your project as you develop it further!

Tuesday, November 15, 2011

How do I get my students excited about Science Fair?

Recently a Wyoming teacher asked us, "I am interested in getting my students involved in the science fair. Where should I start?"

Science Posse coordinator Jan Truchot responded:

It is exciting that you want to get your students involved in Science Fair! 

There are a variety of resources available to you on-line. 
  • If you are interested in your students participating in the competitive aspect of the science fair, you should check out the Wyoming State Science Fair webpageThis page has dates for the state and regional competitions as well as contact information for the regional competitions. Contacting the director of your region might give you some names of people close to you who are already involved in doing science fair.
  • The Science Fair Resources on the Science Posse site 
    • has a link that gives information about rules, regulations and required paperwork.
    • has a series of videos made by the Science Posse that each focus on one aspect of a good science fair project.
    • has an annotated set of links to science fair resources on the Internet
In addition, the Science Posse is available for science fair consultations and mentoring, both in person and virtually.

Please let us know how we can be of further help, or send us a request!

Friday, July 15, 2011

Why do worms come onto driveways and sidewalks when it rains?

In helping out the Answer Girl at the Casper Star-Tribune, the Science Posse was asked Why do worms come onto driveways and sidewalks when it rains?

Answer from Posse member Charles Schmidt:

Dr. Dennis Linden, Cindy Hale, and other worm experts say that worms do NOT surface to avoid drowning. In fact, they come to the surface during rains (especially in the spring) so they can move overland. The temporarily wet conditions give worms a chance to move safely to new places. Since worms breathe through their skin, the skin must stay wet in order for the oxygen to pass through it. After rain or during high humidity are safe times for worms to move around without dehydrating. It is true that, without oxygen, worms will suffocate. But earthworms can survive for several weeks under water, providing there is sufficient oxygen in the water to support them.

Tuesday, January 25, 2011

"The Rare Earth Question: What do the f-orbitals have to do with anything?"

Answered by Graduate Fellow Ashley Driscoll

The Lanthanides are usually placed on the bottom of the periodic table with the Actinides for the sake of space.  This sometimes leads to confusion about how they relate to the rest of the elements and their electronic structure.  Another way to view the periodic table is this:

(From (1), pg. 140.) 

Two important points about the periodic table:
·       Elements of the same Group in the table (same column) have similar chemical properties because their outer-most electron shells are similar (the outer-most electrons are the ones involved in reactions)
·       As you go down the rows of the table (n increases ↓ the table from 1 to 7) the difference in energy between electron shells decreases (from (1), pg. 140):
The first 5 orbitals have very large differences in energy (1s, 2s, 2p, 3s and 3p).  Starting with the 4s orbital, the energy differences between the orbitals decrease and this affects how the orbitals are filled.  The arrow scheme on the right in the figure shows how electrons fill in the orbitals of lowest energy and this follows a pattern of 1s, 2s then 2p, 3s, 3p then 4s (increasing number and s orbitals are filled before p orbitals). 
This order changes once we get to the 3d orbitals of the transition metals (the order of orbital filling can be followed in the periodic table in the first picture by going across the rows from left to right).  Now 3d is filled before 4p, and 4d is filled before 5p (so the lowest number is now not always filled first).  Electrons fill in the available orbitals according to Hund’s Rule by first adding a single electron to each possible slot all with the same spin direction, then the remaining electrons add with the opposing spin to create spin pairs.
The Lanthanides change the orbital filling order again by introducing the f-orbitals.  The f-orbitals have 7 suborbitals each of which holds two electrons.  This requires in 14 electrons needed to fill the suborbitals and results 14 lanthanide elements.  The lanthanide elements are also called rare earth elements, which is a bit of a misnomer because they are relatively abundant in the earth’s crust (1, 2).  The lanthanides have similar chemical properties, with most of the lanthanides forming a +3 (trivalent) ionic configuration (2).  Cerium (Ce) will form the +4 ions, and Europium (Eu), Ytterbium (Yb) and Samarium (Sm) will form +2 ions (2).    The similar ionic states cause the elements to have similar chemical properties, which means they will have similar chemical reactivities.  This has two consequences, the elements occur together in mineral deposits, but that they are difficult to separate (2). 

To purify the lanthanides to their metals, they are first reacted with chlorine (La – Gd) or fluorine (Tb – Tm) to from a neutral complex, such as LaCl3.  This complex is then reacted with calcium (Ca) at temperatures of 1000 °C to form the metal (2).  Fluorine is used for the Tb – Tm elements because reacting them with chlorine makes a complex that is too volatile to process (2).  To form the metal of Yb, the oxidized from Yb2O3 is reacted with La at high temperature (2).  If Yb were reacted with chlorine like other lanthanides, and then reacted with calcium, it would only form YbCaCl2 and not lose the other two chlorine atoms (2).   
Another feature of the lanthanides is the reduction of the ionic radius of the elements as you go across their row in the periodic table.  This is termed the Lanthanide Contraction, and is the result of two effects. Lanthanide contraction in graph form, data from (2):

The first is due to electron shielding.  Remember that the identity of an element is determined by its atomic number (i.e. the number of protons in the nucleus), and as the atomic number increases, we are increasing the positive charge in the nucleus.  With each additional proton comes an electron to maintain a neutral charge.  Electron shielding means that the electrons in an outer orbital feel less than the full charge of the nucleus because all of the electrons of the inner orbitals act as moving screens that reduce net effective charge felt by electrons as you move away from the nucleus.  For example, hydrogen (H) does not have a screening effect because the one electron orbiting the nucleus does not have any other electrons to shield it from the nucleus.  But lithium (Li), which like hydrogen has one valence electron but has a filled 1s orbital, does experience a screening effect.  The one valence electron in the 2s orbital feels less of the positive charge of the nucleus than the 1s electron of hydrogen because the full 1s orbital of Li shields the charge of the nucleus.  This continues as orbitals are filled throughout the periodic table.
The ability of electron orbitals to shield the positive charge of the nucleus decreases s > p > d > f  (1).  For the lanthanides, we’ve seen that the order of filling electron orbitals is a little less straightforward, and a 3d orbital fills before a 4s orbital, and 5s and 5p fill before a 4f.  A quick note, the order of filling the orbitals has to do with energy and filling the lowest energy orbital first.  The relative positions of the orbitals to the nucleus is a bit different; the 4f orbital is between the 5s and 5p orbitals and the nucleus (1, 2).  The 4f orbital acts as a poor shield for the filled 5s and 5p orbitals and so their electrons feel a bit more of the effect of the nucleus and this causes the radius of the atom to be smaller. 
The second is the relativistic effect.  This takes into account when the speed of electrons orbiting the nucleus is fast enough that, due to the theory of relativity, they have an increased mass compared to their mass if they were stand still, or rest mass.  This becomes important for the heavier elements of the periodic table (from about hafnium (Hf) and above) because the increased positive charge in the nucleus causes the electrons orbiting nearest the nucleus to experience greater attraction, which causes them to orbit faster (2).  This makes the radius of the electron orbit smaller, because the radius of an orbit is inversely proportional to mass (so the increased mass from the increased orbiting speed causes the orbital to be a bit smaller) (2).  This effect then carries out over the next shell of orbital electrons and all the way to the outer orbitals because of the strong positive charge concentrated in the nucleus.  This accounts for about 15% of the lanthanide contraction (2). 

With m0 = rest mass
 c = speed of light
v = velocity
m = mass of electron in motion
From (2)

Reference and Figures:
(1)   Gilbert, Thomas R., Rein V. Kirss and Geoffrey Davies.  Chemistry – The Science in Context.  New York: W.W. Norton & Company, Inc., 2004.
(2)   Cotton, F. Albert, Geoffrey Wilkinson, Carlos A. Murillo and Manfred Bochmann.  Advanced Inorganic Chemistry, 6th Edition.  New York: John Wiley & Sons, Inc., 1999.

Monday, January 10, 2011

Culturing Bacteria

A student is culturing some mouth bacteria to compare between humans and canines.  Would it be possible to have a microbiologist identify the bacteria for the type and “amount” somehow?  He will measure the size of the culture on the plate each day but there is probably a better way to quantify the bacteria than measuring with a ruler.  He’ll identify it the best he can with the resources we have, but we thought a microbiologist may have access to better identification tools.  We could also send pictures of the bacteria if they don’t want us to send the agar plates.

Response by Science Posse Fellow Ashley Driscoll

"To estimate "amount" of bacteria a common method is OD600, using a spectrophotometer at 600 nm to measure Optical Density.  The turbidity of the solution is related to the number and gives a pretty good order of magnitude estimate.  One can get a fairly good idea of Genus with colony morphology, size, shape and color, and with a Gram Stain (  A good reference is Brock Biology of Microorganisms and I'm looking for my Microbiology class notes that might help."