Saturday, April 19, 2014

Award Winning Poem

Congratulations to Rebecca Pempeck for her award winning illustrated poem!  She entered in the "Chemists Celebrate Earth Day Illustrated Poem Contest" sponsored by the American Chemical Society.  Rebecca is one of six of my students who submitted entries.  The theme for the poetry contest was "The Wonders of Water".   Rebecca earned second place for the Connecticut Valley regional competition.  Her work will be entered into the national competition.  All of their pieces are featured here.

Rebecca Pempeck's Winning Poem!
Anna Tarplin



Erin McCabe

Breana Lohbusch

Maddy West
Jason Vu

Friday, March 21, 2014

When the Results Matter!

Setting up the gas collection apparatus.
Making a prediction!
I ended the winter term with a short unit on gas laws.  The culminating event for the term was the Target Gas Law Lab (Publication 91654 by Flinn Scientific).  In this fun experiment, I give each group a piece of zinc metal.  They have to use the ideal gas law to predict how much hydrogen gas will be produced when their piece of zinc is reacted with hydrochloric acid.  I love this experiment for many reason:  the kids use a 1-liter graduated cylinder to collect the hydrogen gas (my favorite piece of glassware), they have to apply the ideal gas law to a real problem, and the results actually matter (part of their grade comes from how accurate their prediction is).  They use a paperclip on the zinc metal to suspend it above the acid with a neodymium magnet until they are confident of their prediction. They tape an arrow on the graduated cylinder with their prediction, then pull off the magnet and watch.


Here's a group running their reaction.


Waiting to see if the hydrogen will fill to the prediction mark.
What do you need to know to make an accurate prediction?  The mass of the zinc piece, the temperature of the water bath, atmospheric pressure, a value of the ideal gas constant to match your units,  and the stoichiometric relationship between zinc reacted and hydrogen produced (a nice 1:1 ratio in this reaction).  In the Flinn procedure, there is a "pressure correction factor" step in which you multiply your predicted volume by 9% to account for the vapor pressure of water in the hydrogen gas.  Most of my students used this correction factor, however one group used the direct approach and corrected for the vapor pressure of water by subtracting it off the atmospheric pressure.  Either method ended up with a "ball park" answer, but none of my groups got better then 9/10 for results.  All of the groups predicted a larger volume of gas than was actually produced.  I'm not sure what measurement was inaccurate, but my guess is that the atmospheric pressure was the trouble spot.  But it is possible the the zinc metal I used has some impurities in it, but there was no residue left in the flask at the end of the reaction.  More tinkering is needed to figure out if there was a systematic error, or just nervous students making careless mistakes..

And here's what we did with the hydrogen gas at the end of the experiment.



Sunday, November 3, 2013

Phasing Out the Demo

I’m struggling to make peace with phasing out class demonstrations.  I am in the middle of the transition from a traditional classroom into a student-centered learning environment.  This summer at ChemEd13 I realized that the quest for the perfect chemistry demo is outdated pedagogy that pays homage to the “Sage on the Stage” model of teaching.  As I wrote in my first blog post, Dr. Shakhashiri opened my eyes to the wonderful world of chemistry demonstrations.  Actually, adding class demonstrations to my lessons literally saved my teaching career in my second year.  I dedicated the first year of this blog to documenting how I was implementing new class demos.  Researching demos and learning new chemistry was very exciting for me as I wrote my first series of blog posts.  Yet, now I feel frustrated by the class demo because my students are passively watching me “do science” for them.

Last week I spent a class period doing a series of demos as part of my chemical reactions unit.  After a week in which my kids explored chemical reactions in the lab, I  followed up with some “more exciting” reactions as a way of reviewing their understanding of predicting products and writing chemical equations.  (This is the unit that I presented atChemEd13 in Waterloo this summer.  My fellow chemistry teachers were excited by the lesson.)  The class was going along as planned, my students were sitting around a central lab table, white boards and markers in hand.  After every demo I performed, they wrote out the chemical reaction to describe what they saw.  The eye-opening moment for me was the big finale during my B-block class.  I decided to end the day with my “thermite two ways” demo.  I took the class outside to watch the famous thermite reaction.  There were plenty of oohhs andaahhhs at the awesome power of the thermite, the sparks flying, and the dripping molten iron.  Then, I got out my rusty cannonballs (one wrapped in aluminum foil) and showed them “hand held” thermite.  Banging the two cannonballs together produces a loud pop and sparks.  After I got a good pop and some sparks, I passed the cannonballs to a student.  That’s when the magic happened.   My students got so energized by watching their classmates create the hand-held thermite reaction.  Each successful bang was greeted with cheers and applause.  One boy was crowned thethermite master; he forced some amazing blasts out of those two cannonballs.  I walked away from this day smiling at the great enthusiasm the kids had during class.  But, later that day, as I started reflecting on the lesson, it hit me like a ton of bricks; it only got exciting when the chemistry was in the students hands.  I was reminded once again that learning happens when the students engage in the process.


The flipped classroom has changed everything for me.  When I moved myself from the center of the stage, my goal shifted away from teaching the perfect lesson, and toward creating an engaging learning environment.  I realized that kids don’t learn by watching me blow up things and light stuff on fire.  Yes, I know it’s really fun for everyone, especially me, to do a big “tada” demo.  I am the first to admit that I love demos.  Yet, when I put learning as the central objective in my class, rather than performing, the outcome is unpredictable, rich, and sometimes magical.

Friday, September 27, 2013

How to Jump Onto a Moving Train?!



Heating baking soda using a gas collection apparatus.
Starting over is always tough.  At the beginning of the new school year I was struggling to find the right entry point into the study of chemistry for my students.  I decided to start with an experiment that requires fire, has glassware to assemble, and generates graphable data.   I had the kids decompose baking soda by heating it in a Bunsen burner.  Although this sounds very simple, it turned into a rich experiment to launch my lab-based curriculum.

I found my inspiration for this experiment from the IPS book (Introductory Physical Science - 8th edition by Uri Haber-Schaim).  The opening experiment in this inquiry-based physical science program is to heat baking soda.  As I read through the teachers guide for more details, I came across this statement:  "The original mass of baking soda doesn't matter, more baking soda will increase the volume of gas produced."  That's when I decided to make this into a controlled experiment with an independent variable and dependent variable.  This simple experiment can be easily manipulated to collect enough data to explore the relationship between the mass of baking soda used and the volume of gas produced.

On the first day of experiment, I taught all the students how to light and extinguish the Bunsen burner.

Gas bubbles can be seen in the inverted bottle.
 Once the jitters were out of the way about using the flame, we launched our first round of data collection.  To start off, I had all the students measure out the same mass of baking soda.   I took time to demonstrate how to assemble the apparatus, and then checked each group's set-up before they began heating the baking soda.  I love experiments with apparatus to assemble. This may be the only place in their technology-rich lives that these kids screw a ring clamp to a stand and tweak a tube so that gas bubbles come out inside a bottle.  At the end of the first day, every group could answer to the original question: What happens when we heat baking soda?

Each group used a different mass of baking soda in the second trial.
One the second day, I posed the idea of creating a controlled experiment based on what we had learned about the system.  Through a class discussion, the students generated a question to answer through experimentation.  Once they all agreed on the experimental question:  "Does the amount of gas produced change if we vary the amount of baking soda", each group chose a different amount of baking soda to decompose.  As a class, my students generated a set of data that could be used to formulate an answer to this question.  We plotted a graph of the data, and it gave us a very nice linear trendline.  Now, I have to admit that I was pleasantly surprised when we got a nice graph out of this experiment.  There was so much room for error in this experiment that I was pretty sure that our data would require a lot of handwaving and error analysis to make any sense.

I really enjoyed starting the year with this lab because it has so many introductory concepts all wrapped into one.  The kids learned how to light  the Bunsen burner, they designed and implemented a controlled experiment, they leaned how to measure the mass of a powder and the volume of a gas, they assembled apparatus to collect a gas, they plotted a graph of their data, and answered an experimental question.  I call this a home run in the first week of chemistry class.
A graph of my class data, not bad for the first experiment of the year.

Friday, August 2, 2013

Presenting at the Generations Symposium


The Generations Symposium Presenters
The Generations Symposium is a special event at ChemEd in which young teachers and students work with mentor teachers to present chemistry demonstrations.  Micaela and I were fortunate to have the opportunity to participate this year in Generations.
Micaela doing the Singing Flame Tube demo.  It was a huge hit!
We were the lead-off group for the symposium because we were a last minute addition to the program.  When I introduced Micaela to the packed crowd, and explained that she was just hired to teach chemistry only three weeks ago, she got a huge round of applause.  I must say that she was an incredibly good sport about the presentation, seeing as I only told her about it after we arrived in Waterloo.  And, I think she had a lot of fun doing the demo.
Charging the tube with rubbing alcohol.
We presented our "Singing Flame Tube" Demo to the group.  This demo is a nice (and safer) variation of the classic Whoosh Bottle demo.  I have an 8-foot polycarbonate tube that's about 2" in diameter, which I brought all the way from Pomfret for this event (it was totally worth it).  First you stopper one end, then pour about 50 mL of rubbing alcohol in the tube.  Next you stopper the other end, and twirl the tube for a few minutes to distribute the alcohol evenly and vaporize some of it.  Here's the most important step:  you must drain out the excess alcohol into a beaker.  Once you've drained the excess liquid, you hold the unstoppered, alcohol-charged tube over a candle.  It's a show stopper!

Andy and his granddaughter doing a demo together.
Another wonderful part of the Generations Symposium was Andy Cherkas's presentation with his granddaughter.  Andy is one of the "old-timers" at ChemEd, a teacher who's been part of this great conference since it began 40 years ago.  He and his granddaughter gave a fun presentation about the invisible spaces between molecules.  Andy is literally transferring his love of science to the next generation.



Star Wars Re-enactment through chemistry demos
The group from Duke University, led by Ken Lyle brought down the house with their Star Wars reenactment through chemistry demonstrations.  They presented a choreographed demo show, set to sound clips from the Star Wars movies, that included a battle scene with light sabers and the struggle between good and evil.  They used flame tubes, chemiluminescence, photosensitive tiles, a flame tornado, and hydrogen balloons in their presentation.  In a word, Awesome!



The Star Wars group had it all:  flames, glowing reactions,
hydrogen balloons, choreography and costumes!
The best part about the Generations Symposium for me was to see how young teachers and students are excited about chemistry education.

Monday, July 29, 2013

ChemEd13 Lab Workshop: Exploring Chemical Reactions, Bringing Chemistry to Life

Let's face it, chemistry teachers are happiest in the lab!

Today I taught a workshop for chemistry teachers at ChemEd13 on my favorite lab of the year:  Classifying Chemical Reactions.  This is a lab that I have adapted from a Flinn Scientific book; each year implementing small changes.  In the latest edition I added instructional videos embedded into the lab handout for my students to watch while conducting the lab.  This year I finally felt that the lab was "done enough" to present at ChemEd.

I had a good turnout of teachers for my workshop this morning, on Day 1!  These enthusiastic teachers dove right into the lab.  Once we finished the lab stations, I taught the group how to do a series of demonstrations that go along with the unit.  I encouraged teachers to try the demos for the first time.  Even Michaela, my new colleague, got into the act by performing the "Singing Flame Tube" demo today for the group.  It was great fun to share some of my favorite chemical reactions here at ChemEd13.  Thanks to the wonderful folks at the University of Waterloo for providing all the chemicals and equipment for my workshop.


These teachers are writing the chemical reaction for what they just saw.


His first time lighting the famous Whoosh Bottle demonstration

Learning how to do the classic "Death of a Gummy Bear" demo.

My new colleague, Micaela, burning magnesium ribbon.
Jean and I at ChemEd in 2007.
ChemEd is a wonderful opportunity for chemistry teachers from all over the world to come together to share ideas and learn from each other.  I love coming out for this fun conference because it's great to be around so many people who love to teach chemistry!  One of my favorite parts of ChemEd is connecting with my chemistry friends.  Here's a picture of my good friend Jean Hein during my first trip to ChemEd in Texas six years ago.




These chemistry teachers are working through the 8 lab
stations for the Chemical Reactions Lab

Friday, May 17, 2013

Looking at the Absorption Spectrum of a Star



Josh, Sharon, and Honors Chemistry Students in the observatory

Josh is so excited that he can't stand still for a photo!
How many years does it take to get a project off the ground?  In this case, two.  Josh, the astronomy teacher here at Pomfret, and I have been batting around the idea of using our observatory to collect star spectrum data as a chemistry lab.  We do the traditional spectrum lab with gas tubes in the classroom every year.  Why not take the next step and look at the spectra from some stars?  Josh found the tools we needed to make this idea happen.  RSpec makes a diffraction grating attachment for telescope cameras that will generate spectra from stars and the software to analyze the data.  http://www.rspec-astro.com/  We can also use this same software to analyze the line spectra from our gas tubes in the lab.  Our plan is to collect some data for select elements in the lab using the gas tubes, analyze the data in RSpec, and then move to the observatory to collect data for some stars.  We are both really excited about the possibilities.

Jack and Chris are very excited about science.
This week we took a group of my Honors Chem students over to the observatory to give them a tour of the spectra data and analysis.  We didn't do a full lab with these kids, but we introduced them to this exciting project.  Josh and I were both feeling a bit unsure about the night at the obs because the end-of-the-year crunch is upon us.  However, being there with the kids showed us how exciting this kind of science project can be for everyone.  Josh was so inspired that he wants to change our curriculum to an "Astronomy First" department instead of "Physics First".  Next year we will start the year with this project.  Today at lunch we made a plan to use some of our summer vacation to solidify our goals and methods for collecting and analyzing star spectra.  Why not start the year with this exciting project.   Who knows what direction it will take us...
We also got a wonderful view of Saturn.  Sarah and Rachel were excited to see the rings.