Classification of Matter "Sandwich"

Watching the Iron and Sulfur reaction.

Classification of matter (COM) is usually the first "real" chemistry topic we tackle in a new year.  This  year I decided to make a "Lab Sandwich" with my classification of matter unit.   I also like to think of this unit as a pyramid, a swimming reference that seems to fit the symmetry of the unit.

To open the unit, I gave my students a mixture of iron, salt, sand, and pebbles to separate.  The lab groups made a flow chart with a detailed plan for obtaining pure samples of each of the four components.  As an extra challenge, I asked them to collect enough data to calculate the mass percent of the parts of the mixture.  I love starting the kids off with an inquiry lab that they really can't mess up.  This particular mixture demonstrates several different physical properties and gives them a chance to learn some basic lab techniques.  This lab is loosely based on Separation of a Mixture found in Flinn ChemTopic Labs:  Volume 1, Introduction to Chemistry.

The pure samples of iron, rocks, salt, and sand (green and brown sand).

Students working through the "Classification of Matter" POGIL

The meat in my COM sandwich is a POGIL that makes the transition from macroscopic observations of matter to the molecular level of matter.  I love this POGIL because the students get an introduction to chemical formulas and a hint of nomenclature along with a particulate perspective on elements, compounds, and mixtures.  This great activity is found in POGIL, Activities for High School Chemistry by Laura Trout.

Sorting the "samples" into elements, compounds, and mixtures.

Watching the iron-sulfur reaction.

The final layer, the icing on the cake you could say, is the famous Iron and Sulfur lab.  The Iron Sulfur Lab This lab is a classic, and we consider it a rite of passage for our chemistry students at Pomfret School.  In this lab, the students study the mixture of iron and sulfur and then they react the mixture to form the compound iron sulfide.  This is also an exciting lab because it's the first time the kids get to use the Bunsen burners.  The comparison of the physical and chemical properties of the new compound and the mixture of the elements is a wonderful culmination to the COM unit.

My labs are all over instagram!

The smell is all part of the experience.

Getting to Know You!

Students are looking for the mystery person on the card.

This year I decided to try a new "ice breaker" activity with my students to help get the students interacting with each other on the first day.  I handed out a 3x5 index card to each student in the class. The kids  divided the card into four sections by making a line down the middle in both the x and y direction.  In the top left they wrote their hometown and their dorm.  In the top right they wrote their favorite subjects in school.  In the bottom left corner each student wrote a word to end the sentence "I'd rather be...".  And the most challenge part of the card was the bottom right:  a random fact about yourself.  At this point there were no names on the cards.

When all the cards were completed, I collected them, shuffled the deck, and passed them out randomly

"Is this you?"

to the kids (only one person got his own card back all day, it was a lucky day!)  Here's where the kids had to get up and mingle; they were charged with finding the person represented on the card.  Once they found the correct student, I asked them to introduce themselves and talk about the facts shared on the card.  My students looked around the room for a few moments, wondering if they really had to stand up to do this activity.  I encouraged them all to get out of their chairs and mingle, and begin the search for the mystery person on their card.  With a little prompting, my students stood up and began talking to each other.  In about five minutes, the kids had all identified their mystery person.  At this point, I asked all the students to write their names in big letters on the back of their own card.

Our international students have so many interesting experiences.

The final part of this activity was to use the cards to find two other students in the class with similar interests.  Each self-selected group had to have something in common, using the information on the cards as a launching point.  As the kids divided up into groups, I checked in with them to learn what they had in common.  One group of three boys teamed up because they were all the youngest siblings in their family.  Another group formed because they all played musical instruments.  Three girls formed a group because they all love the beach.  I really enjoyed watching kids try to find common interests to form a team.  Once all the students had identified a group with similar interests,  I announced that this was their first lab group of the year.  The teams each received a sample of a mixture (iron, salt, sand, and rocks) that they had to separate and determine the percent mass of the mixture.  They were excited to learn that their group was staying together for a lab project.

Who can disagree with these favorite classes?

Over the next few days, I used the cards to practice the kids' names while they conducted their experiment.  I took advantage of the information on the cards to ask questions about each student's interests and hometown.  It was so nice to have a conversation starter to begin developing a relationship with each kid.

On the first quiz at the end of the week, I used their cards to make a "Who Am I" extra credit question.  Using the cards once again, I wrote a statement describing each kid in the class.  Everyone got at least their own clue correct on the quiz, but more importantly, the kids asked around to identify their classmates from the clues when they got their graded quiz back.  I included a different clue about myself on each quiz too.

Using this simple get-to-know-you activity has started the class off on a positive note.  The students got a chance to learn about each other, and I layed the groundwork for  a positive learning environment by taking time to meet each of my students.

Worthy of Mr. Wizard

Thank you to Linda Goodwin for writing my first guest blog post and to Jim Goodwin for providing these wonderful pictures of the event.

Linda is feeling the force from a spinning gyroscope.

The group of science enthusiasts at the Pomfret Library.

My husband’s idea of the perfect science teacher is Mr. Wizard from 1950s TV. He performed chemistry experiments with ordinary household substances and made it all fun. Sharon’s demonstration last night at the Pomfret Public Library was definitely worthy of Mr. Wizard. 

It was the culmination of the adult summer reading program with a science theme.  

Brian demonstrating rotational inertia.

Her husband Brian presented some physics demonstrations about magnetism and sound waves, and Sharon focused on acids, bases and pH, with hands-on participation. 

Interacting with a gyroscope.

She kept us mashing and liquefying while using cabbage juice as the baseline pH indicator. We then tested other natural substances to find their usefulness as indicators.  Kids as well as adults joined in.

Sharon and Micaela make the pH Rainbow with Red Cabbage Juice

When that was finished, we adjourned to the outdoor deck to see a long tube fill with gentle flames over a votive candle and from Brian more flames reacting to sound waves in music.

Testing the pH sensitivity of natural pigments.

Sharon prefaced her presentation by saying how much she liked to do community outreach. This is the third time I’ve seen her in action and I can truly say she conveys the message of science as an enjoyable and useful subject, just as a science ambassador should.

A Week Immersed in AP Chemistry at Goucher College

Now that it's the first week of August, it's time to get started on my planning for the fall.  I'm so grateful for these wonderful teachers I met at the AP Summer Institute at Goucher College in June.  Together we dove into all aspects of the AP Chemistry curriculum.  We had a lot of fun and we learned so much together.  I wish that all of them were close enough to meet for coffee during the school year!

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

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.

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.