This. Is. INQUIRY!!

I was fortunate enough to have a quality secondary science education program in college.  They made sure we were in the classroom a lot.  Not just middle/high school, but I had to go to an elementary school twice a week for a whole semester and teach a week long science unit.  That was one of the most valuable parts of my college education.  Pose a question to a group of second graders, 25 hands go up shaking and waving (how come this doesn’t happen in high school???), wanting to give an answer, and you get a real good idea how good your question was.

My program (this was 12 years ago) stressed inquiry.  Going into my first methods teaching class, I thought I knew how teaching was going to go.  Give them a book, do some experiments out of lab book, test.  Wash, rinse, repeat.  After presenting the word inquiry and a few activities that were inquiry-based, I went home that night imagining how much fun teaching could be.  And I thought about how much I missed out on in high school.  I loved those rare lab days where we were able to “experiment” (um, follow directions).

Our professors encouraged us to go to conferences when we could, mainly NSTA, to grab ideas from teachers doing great things.  If you’ve never been, I encourage you to go (especially a national one if you can swing it).  Through the years, I’ve collected what I’ve thought were pretty good guided inquiry labs.  I’m sure there are better ones out there, so please share if you’d like to add to the list.  Since I teach mostly chemistry, they lean that way.

#5.  The Hindenburg Lab

There’s nothing better to most high school students than something that explodes.  I like this lab as a lead-in to stoichiometry.  Essentially, I give them two reactions, one that produces hydrogen (they could figure this out, but I use whatever I have on hand like Zn/HCl), and another that produces oxygen (peroxide/KI…this is a reaction that wouldn’t make a lot of sense to them at this point…great reaction to introduce catalysts).  They take their “blimps” (plastic dropper bulbs) full of water, play around with combinations of Hydrogen and Oxygen, and spray them into a flame.  When the timing is right, we’ll turn it into a contest for the farthest launch in the hallway.  Afterwards, ratios, rocketry, and history are a great way to wrap it up.

#4.  Balloon in a Flask

Here’s a balloon.  Here’s a flask.  Get the balloon to coat the inside of the flask.  This comes after chatting about pressure and the atmosphere.  A classic demo, but let the kids figure it out.

#3.  Burner Flame

I came up with this (I think) as an open ended assessment at the end of a thermochemistry unit.  I don’t know how accurate the numbers are, but it works out pretty well to get them thinking.  I give each group of students a coin (penny, nickel, etc.) and they have to determine the temperature of a Bunsen burner flame using the coin.

#2.  Take Home Challenge

I wish I had more ideas for things that students could experiment with at home.  I’ll take some sand, salt, iron filings, and poppy seeds, mass them individually for each baggie, number it, and hand one to each student.  They are instructed to separate them in to four separate piles, bring them in, and mass them.  This is a great way to revisit properties and separation techniques.  It is an old idea, but let the kids play around at home.  It is a great way for some parent interaction at home.

#1.  This is by far the ultimate in chemistry inquiry.  The methods/thinking vary so much, but with a lot of struggling, a confident answer is usually made.  I think it fits well at the end of a stoichiometry unit, but lately I’ve incorporated into a final.  Enjoy.

Baking Soda decomposes at high temperatures.  One of the equations below is empirically correct.  Show your work and explain your tests/procedures.

NaHCO_3(s) –> NaOH_(s) + CO_2(g)

NaHCO_3(s) –> Na_(s) + C_(s) + O_2(g)+ H2(g)

NaHCO_3(s) –> Na₂CO_3(s) + CO_2(g) + H₂0_(g)

NaHCO_3(s) –>Na₂O_(s) + CO_2(g) + H₂0_(g)

 

Contact me if your interested in more details.

Food

I elect not to use a chemistry book in my introductory chemistry class.  The last time we were up for curriculum money, our department spent a lot of it on technology that would help us teach.  There are some books in my classroom, and I’ve even had students ask to borrow one (this is rare).  I obviously supplement quite a bit, so they end up with a binder full of good stuff by the end.  The nice part is that I get to pick and choose what goes in there.

Without a book, how do students read about chemistry?  I’ve decided to make most, if not all of our readings, revolve around food.  There is so much chemistry in the food and beverage industry, and I think it is something that is interesting for the students to read about.  I even have a standard in my class that revolves around food and food additives.  I’ve found some great articles on archive from Chem Matters, where you can look at some of their archived articles (for free!).  There is almost always something about food (and other interesting topics), and I have used the articles on corn, chocolate, caffeine, and artificial colorings.

One of the labs I love to do, that really doesn’t interest the students until afterward, is on pop (that is what we refer to as a carbonated beverage in the north).  I’ll ask the students to bring in a can of pop from home or buy one at the store.  Most have one laying around at home, but a number of our students don’t have any in the house (which I’ve found fascinating).  We’ll flatten it by pouring it in a flask and shaking it a bit.  It works perfect to do it on a Friday and let it sit until Monday.  I always do this in the middle of a density unit, and challenge them to find the densities of the pops that were brought in.  Following a lab where they had to find the densities of water, rubbing alcohol, etc., this isn’t tough for them.  They’ll measure 6-8 pops (use and analytic balance or one that will get to 0.001 g) and put their numbers on the board.  As this process is very boring, the data lends itself to a great discussion, and it takes about 30 minutes.  As they put the numbers on the board, like clockwork, the diets are less than 1.00 g/ml, the regular pops more.  Obviously this leads to a great discussion on sugars, artificial sweeteners, ingredients, and of course, how these (sugars or lack thereof) affect density.  I’ve collected dozens of unopened cans over the year, and we’ll pull out the aquarium for a nice visual (the diets float).

Somewhere along the line I’ll have them compare the ingredients of a few pops.  There are some classics that always spark conversation (brominated vegetable oil, glycerol ester of wood rosin, gum arabic), and I’ll encourage them to do a little research.  There is a purpose to all of these (for the pop), but it gets the students thinking about what they put into their bodies (and how much).  Show them what 48 grams of fructose looks like.  And who drinks a can anymore?  Most of them down the 20 oz. bottles.  I always take a chance to read a little excerpt from Schlosser’s “Fast Food Nation”.  This is a fantastic book, but there is a section on flavor additives that is just outstanding.  They even list all of the chemicals needed for the strawberry flavor in a milkshake at Burger King.

One final discussion we have is about the actual densities and error in the lab.  They all want to look up the actual densities on the internet (Google it!), but that is actually tough to do.  I’ll give them a little class time to call the 1-800 numbers on the can and talk to the company.  They are shocked when someone from Coca-Cola gives them an actual density from their database.  All kinds of things come from these phone calls (they love using their cell phones to do this).  Some companies won’t give out their numbers, some companies don’t have these numbers, students love to compare how nice each company was to them on the phone, and some companies give different units (kg/L is a popular one that we didn’t measure in class, but we can convert it!).

At the end of it all, I’ll give them a lab practical in which they are required to layer 5 different pops on top of each other in a given test tube.  They have a set amount of time to do it, and what I love about it is they all know what to do (they have the class data), but it is a struggle to actually create a procedure that works and get it done.

The Six Bottle Dilemma

This semester I have an advanced chemistry class of 25.  With our sized school, we’ve opted not to go the AP route to better serve our student population.  I don’t think I’d be able to get through the AP curriculum on our schedule anyway…which is fine by me.  This is by far the biggest class I’ve had (compared to 16 students a year ago).  I love the participation (25% of the senior class), but finding enough equipment is a nightmare.  The class is essentially a continuation of chemistry, as we hit on more topics at a faster pace.

One experiment I love to do is the “Six Bottle Dilemma”.  This is nothing new…pick six soluble salts, put them into separate vials with droppers, label them A-F, and add  water to each.  Students mix them (A+B, A+C, etc.) and observe.  I tell them the chemicals and they have to match it up to the letters.  I’ve done variations over the years (with different chemicals), while introducing net ionic equations.  Back in the day when not everyone had the internet, this proved to be tricky.  Since the internet has evolved into being in the pocket of our students (90% of our kids have smart phones), this lab has lost some of the critical thinking elements.

I know, as well as the students, that I can’t prevent them from getting on the internet.  What is their response when they don’t know an answer or they don’t know what to do?  Google it.  I don’t blame them, I’m just as guilty.  That is the type of student we now teach.

In an attempt to have them use in-class resources (CRC, a few chemistry dictionaries, FLINN chemicals section, etc.), I wanted them to solve this using the books (and in turn, learn how to use them if they wanted to look something up).  I required them to cite what they used to solve each solution, and the internet was not one of the options.  My other goal was that I wanted them to think.

They enjoyed mixing the chemicals and seeing the colors (who wouldn’t?).  The moment of sheer confusion as they finished was priceless.  I’ve shown them the CRC and have encouraged them to use it, but it is really intimidating.  Most of them went the route of finding what was soluble/insoluble from the reactions, and they use a fairly standard solubility table they’ve had for a while.  “What does partially soluble mean on this table?”  “What does it mean when it says the compound does not exist?” “What does it look like when it decomposes?”  How much chemistry can come from these questions?  As they get more comfortable with the CRC (and other books), these questions answer themselves (which are GREAT questions).

In the end, every group was correct (I do give each group a different grouping of A-F, so each group has the same results, but with different letters).  Did some use the internet?  You bet they did, why wouldn’t they?  They did have to use the resources in the book though, and I am under the impression they had to think.  I didn’t give them a whole lot of class time (it is hard to share 2 CRCs with 25 people), but several groups spent hours of their own time pouring over the pages.  When they turned it in, they knew they were right.  Some weren’t so sure, but I didn’t see them spend much time on it.

Finding the colors of precipitates was obviously quite helpful.  My favorite was the student who noticed the stock bottle of silver nitrate solution always had black deposits on  the dropper.  He made that connection to one of his droppers being black.  Awesome!!!

If you want the rest of the chemicals I’ve settled on, I’ll email them to you.  I definitely would not trust my intro chemistry students with them.

Popcorn!!!

In my previous post, I talked about significant figures.  There are great ideas out there in terms of what people do.  I’ve also found in my discussions on significant figures, kids really struggle reading the instruments correctly (decimal places).  I put out all kinds of different equipment, have the kids write their measurements on the board, and talk about why people wrote what they did.  I also have random lengths of PVC with random scales I’ve created on those PVC pipes.  I’ll hold them up to different lines on the board, and conversations ensue.

After some of this practice, I try to find something practical for my students to explore.  For the past few years I’ve used popcorn.  Enter a bit of inquiry (a word that has many levels and layers to it), as I challenge my students to figure out a way to find out the percentage of water (by mass) in a popcorn kernel.  They come up with an idea, run it by me for safety (I would recommend not allowing oil…I allowed it once, and we had a small grease fire), and try it.  Most of them come up with the idea of popping it, others crush it with a mortar and pestle.  The popping is the fun part as they come up with some crazy/creative/interesting ways to do this.  After many burnt kernels, a method is perfected, and they become a well oiled machine, pumping out data.  Some move to multiple kernels with multiple trials, and data is plastered all over the board.  I bounce around answering a lot of questions about significant figures and decimal places, as this is their first chance to apply their sig fig knowledge.  There are many balances in my room, which I encourage all of them to get used to “keep the lines short” in hopes of getting some different results to discuss.  This year I made available two completely different brands of popcorn as another variable.

The biggest complaint (I always have my students reflect on each lab experience…it is a great way to get more ideas) is that there really isn’t too much variety in the lab.  I would agree, which is why I try to gauge the classroom feel for the lab.  Some complain there wasn’t enough time to get done what they anted to get done.  Most are amazed at watching an individual kernel pop.  The physics part of me would love to measure the energy released in a popping kernel.  I also want to get one popping on a slow motion camera.  And I always ask them why the bag of popcorn is always really steamy when you open it out of the microwave.  Speaking of microwaves, a great way to talk about a completely different kind of cooking.  And yes, there is always a group that requests a microwave for this lab.

Significant Figures….blech

Oh, the most glamorous part of teaching chemistry.  I dread the day I have to introduce these little beauties (as if they were actual beings), but I’m so happy in the end not to have to say, “Just round it to whatever.”  Maybe some teachers out there avoid them, don’t find the use for them, or just don’t get the whole point behind the system.  It is really one of those concepts that I feel not many kids understand.  Don’t get me wrong, they can learn the rules and apply them, but do they really get the point behind it all?

I’ve never really come up with a creative/unique way to teach about sig figs.  If anyone has some great ideas, let me know.  I’ve come to the conclusion that some things just aren’t meant to be cool/fun/sexy/exciting in chemistry.  Sometimes it just has to be, “Here it is.  Practice.  Practice a little more.  Now let’s use it.”  I’ll post a lab that I do which attempts to produce data showing the value or point to sig figs in a bit.  The one thing I do like is it sets up the math for the whole year.  We do apply it to anything we do and in chemistry, a lot of the measurements are pretty small.  What do you do?  How do you do it?  If you don’t, how do you get around it?  I know I struggled with it in college as the professors expected us to know how to use them.

This is really aimed at a small part of the population that has even heard about significant figures.   My apologies in advance.

Mystery Powders

We began our semester a few weeks ago, so I am basically going through my chemistry curriculum for the second time this year.  I had three classes in the fall and two more this semester.  Since we are on a block schedule, I have taught this class somewhere on the order of 22-24 times during my career.  I’ve found this is a great lab to go with early on.  It is relatively safe (in terms of a chemistry lab), it involves fire (which is perfect for 17 year old boys), and is essentially a puzzle.  All the while, I weave different pieces of equipment, observation techniques, chemical/physical properties and changes, and the nature of science into this lab.  It uses quite a bit of class time, but I always come back to depth over breadth.  Most of them have pretty positive things to say about it when it is all said and done.  I’ll present what I do, and I’m sure there are some great twists on it out there.  I’ve tried quite a few over the years.

My teacher prep program in college was top notch.  They were very heavy on inquiry and using a “learning cycle” approach (lab first, then content, then application) to teaching.  As all programs have their own rationale on how science should be taught, I came away from my methods classes with a much different approach to teaching than what I, and most people, experienced in high school.  I just liked chemistry, math, and physics, and thought that trying to teach it would be fun.  Little did I know that there were different ways to teach than using a textbook and answering questions at the end of a chapter.  Little did I know that a lab could be done without a lab manual telling you what to do.  One of the first things I remember doing in my methods class was this lab.

This is a lab in which I hand nothing out to the students.  It is set up so that the lab has different phases, and as each one is approached, a small discussion of what to do precedes that particular part of the lab.  I begin by giving them “my” objective.  This lab has a bit of guidance, but once they get going, it opens the door to more experimental design.  I hold up a film canister (remember those black ones with the grey caps?  Go to a film developer and ask for every one they are willing to part with.  They make fantastic containers and are slowly going away).  Inside the canister is a mixture of white powders.  Their goal (in the end) is to figure out what is in the canister.

After many long, blank stares, I set up the first part of the lab.  They are presented with five canisters labeled A, B, C, D, and E.  Inside each of them is a powder that they will become very familiar with over the next week (I never tell them what the powders are until after the lab reports are turned in).  The first phase of the lab is simply observing.  I tell them that I expect at least 10 observations on each powder (which is a tough task).  I also guarantee them that I will look over all 50 observations before they will move on (I do and I am pretty particular).  We’ve practiced observing some random objects, so they do have some background in observing things, and what constitutes a decent observation.  Off they go to investigate.  The only rule is that they can’t taste them (which they will want to later).

Round two involves the testing (which they find much more exciting).  We first introduce the Bunsen burner and how to light it.  I show them my version of a small cup made out of aluminum foil.  Putting a small amount of powder in the cup and heating is a test they can do (once their observations are checked).  I also present them with three small bottles of liquids (1, 2, and 3).  Adding a few drops of each to each powder will provide some results.  Combining these test results with the observations, they will almost be ready to solve their mystery powder.  After the tests are done, I recommend testing combinations of powders (as they all will have at least two powders mixed, more likely 3-4).  I also tell them they can do some practice mystery powders, having their partners whip up a mixture for them.  After they feel like they are ready, they come up to me, I give them a canister with a number on it, and they are ON THEIR OWN.  One of the best parts of the lab is that each student gets their own powder.  They work with partners observing and testing, but everyone is on their own when it comes down to the mystery powder.  Some take five minutes, some take five hours.  Depending on how you want to grade it, I tell them how I will grade it before they begin.  I think it is important they know this up front.  They also don’t get to know their answer until they turn their report in and get it back (which I always get back to them the next day).

There are so many little things that come out of this lab.  I refer back to it all semester.  They also remember it well because they have a lot of time with those powders.  From setup to the final cleanup you are looking at four to five days on an 84 minute schedule.  I require them to do two mystery powders, which seems to be the right amount.  Obviously there some prep here, but once the canisters are labeled, it cuts the time in half.  Powders and liquids are listed below.  I’ve tried a lot of different powders, including adding powders, but this combo seems to work the best.  Let me know if you have any twists or questions, let me know.

A-Salt

B-Sugar

C-Corn Starch

D-Baking Soda

E-Dishwashing detergent (tough to find any without the greenish/blue specs in them)

Liq. 1 – water

Liq. 2 – vinegar

Liq. 3 – Iodine/KI in water