Unit 4 Reflections: Worksheet 1 and Electrolysis of Water

Going by the modeling "book" is not working for me lately.

Friday: I expected pure substances vs. mixtures to be a review for my students, especially after the feedback I was receiving in our post-lab discussion.  The topics are covered heavily in physical science. The students usually blow right through it in years past.  I thought it would be a great chance to squeeze in some much needed textbook reading/writing practice, with it being a familiar topic that is not all that difficult to grasp from reading.

Um... no.  That's not how it went with these students.

Friday, in class, they were assigned to read the (very short) unit out of the textbook on classification of matter.  They were then to write me a paragraph classifying the stuff we saw in the lab (salt, sand, iron, salt/sand/iron together, water, sulfur, iron, iron sulfide) as a pure substance or a mixture using vocabulary they read in the text.  I figured after they read about the topic, we'd jump right into Worksheet 1 on Monday.

What they actually did instead of reading-- sit with the book in front of them without flipping a page, then turned in a list of garbage that showed they didn't even as much look at the headings on the pages.  Not cool.  I know it was Friday, but COME ON.

So, I got to spend all of Monday reteaching what they didn't read in the book.  I did it in a PowerPoint that I've used in the past, then finally gave them Woksheet 1.

I've never understood why this is so hard for students:

I used to assign a similar worksheet in years past and my students went into panic mode when they saw it.  After my Modeling Workshop, it occurred to me that I was assuming that students had a conceptual picture of particles when it was something I truly never taught.  This year, since we have been explicitly working in conceptual "particle" mode all year, I didn't anticipate it being nearly as panic inducing.  Wrong again.  *head desk*

So we wasted more time today slooooowly correcting the very wrong answers on Worksheet 1 until it finally seemed like my students had some idea of the difference between elements, compounds, and mixtures.

Onward ho-- next we were supposed to start building towards the Law of Definite Proportions with a demonstration using a Hoffman Apparatus.  My Modeling Workshop was generous enough to provide us all with our very own Hoffman Apparatus!  Unfortunately, they didn't give us a power source.  Never fear, they told us, you can just use a 6V or 9V battery.  Ha.  Hahaha.  Ha. Of course, I procrastinated until the last minute to try this idea and found that while a battery will cause some decomposition, I could not get the reaction to go nearly fast enough to be visually impressive.  Maybe it was just me.

I needed a backup plan.  My first thought was to do the 9V battery/pencil lead electrolysis of water-- but a single set up is way too small for an effective demo.  Plus, I really wanted them to see that it was twice as much hydrogen than oxygen, and actually prove it was hydrogen/oxygen and not just bubbles.

Thanks to Google and YouTube, at the 11th hour I was able to rig up some of these setups using materials I had on hand:

Small plastic container with two push pins through the bottom, 2 test tubes, a 9V battery, and a solution of water with a small amount of sodium biocarbonate

The containers were a little cumbersome to manipulate, but the setup worked well overall.  Between weak batteries and time constraints, we didn't see a perfect 2:1 ratio, but the students clearly saw more gas being formed on the cathode side than on the anode side.  I was able to come around with a flaming splint and demonstrate the hydrogen "pop" to each group.  There wasn't quite enough oxygen to re-ignite a hot splint, but it was enough to at least make the flame visually grow.  We discussed how water vapor would not cause a flame to grow or pop-- too much water vapor may even extinguish a flame.  We also discussed that the container did not feel hot enough to be boiling, so it couldn't be "boiling" water.

I told them that scientists have found that a compound of a substance always has the same ratio of elements.  Water is always 2H:1O.  We then hypothesized the ratios of elements in other familiar compounds, like sodium chloride and glucose.

We were going to watch "Gases and How They Combine," as suggested by the lesson plan.  I watched the video myself on YouTube and it is BORING and dated.  While the demonstrations and explanations are great, I don't see my students paying enough attention to get anything out of it.  I think we'll jump right into Worksheet 2 tomorrow... then on to Dalton's Playhouse.

Despite being dreadfully far behind and feeling like 50% of my students are shut down... I do hope that by the time we get to balancing equations, it should be a non-issue.  That's basically all they are doing in Worksheet 2.

Unit 4 Reflections: Separating A Mixture

I've had to shake things up a lot.  Last week, we had two more snow days and two days where I lost my students to standardized testing.  I basically said to heck with the rest of Unit 3.  We didn't do any of the specific heat calculations.  We quizzed on the types of energy, energy bar charts, heating/cooling curves, and phase diagrams (my addition) and called it a loss.

I'm also shaking up Unit 4 a bit.  For starters, it begins with demos and discussion.  Unless I'm blowing something up, my unmotivated, under engaged juniors don't give a darn about demos.  And I've been struggling all year to get my students to buy in to group discussion-- it does not happen easily.  I truly needed to get them in the lab.  I fell back on the old "Separation of a Mixture" lab, an activity that I usually do at the beginning of the year to introduce them to the concept of experimental design and properties and mixtures.

We started Unit 4 by defining properties, then differentiating between physical and chemical properties.  I then gave them a sample of salt, sand, and iron filings and asked them to develop a plan, using their properties, to separate the three substances.  I offered them a list of available materials to help them out.  Considering I rushed them a bit on their experimental design process, they didn't do too terribly.

Overall, I was really impressed with my student's white boards with the exception of their particle diagrams.  I was very specific for the verbal this time:  I asked them to answer the question, "Why were we able to separate the three substances?"  I was very specific for their math as well, and told them to show me how to calculate the percent composition of the mixture.  I left the graphing and particle diagrams completely open ended, asking them to do what they felt was appropriate.

Most boards looked like this:

Strong answers to the questions, good math, appropriate method of graphing data, dreadful particle diagrams (WTF?), and an overall inability to spell the word "separating."

We addressed the particle diagram issue today.  I hope they got the point-- everyone was utterly braindead today.

Unfortunately, many of my lazy students have caught on that I don't actually grade whiteboards.  So, several groups produced garbage like this:

At least they figured out how to calculate percent composition...

Um... yeah.

I also performed the demonstration of heating iron and sulfur.  This is a demo I had never done before.  I could not get it to react with a hot stirring rod or hot splint.  I ended up using a ring stand, a heavy watch glass, and a bunsen burner.  The odor is horrific and the ignition was not all that impressive to the students.  I think the bunsen burner flame confused them- they just thought it was flammable even though I made a point of showing how far away the flame was from the iron ring.  But, they were able to see that we got a substance with different properties from either of the original two substances.  We left off with a textbook reading about pure substances vs. mixtures.

We'll do worksheet 1 on Monday.  I haven't shown them fractional distillation equipment (we don't even own any), so I suppose I should do that first!  Youtube here we come...

On a side note, my students had to take a district wide benchmark test today.  It was created with traditional pacing in mind, so many of the topics we have not covered.  When I flipped through the test, I figured there were about 11 out of 30 questions that my students should be capable of answering.  I was at least encouraged to see that my students mostly got those 11 questions correct.

Unit 3 Reflections: Icy Hot Lab Results

This is becoming the semester from h*ll.  Seriously.  Between implementing the chemistry modeling curriculum for the first time, the exceptionally unmotivated group of students, and the ridiculous number of interruptions, I'm ready to throw in the towel.

The good news:  my students' data came out better than expected.  Even in my first class, students were able to note a difference in the shape and slope of the heating and cooling curves at different points.

Some of their curves:

The bad news:  everything else.

I think maybe a handful of students at best understood what I think is a pretty easy concept.  A heating/cooling curve will have parts of the line that show little rate of change (flat) because the energy is being used to "break" the forces of attraction between the particles and change the matter into a different phase.

I don't know exactly what it is that I'm doing so terribly wrong, but I cannot get these students to care for the life of me.  I can't even get enough intrinsic respect out of them to try for me.  Two of my students today told me they hate everything about science.  I can't even fathom having the lack of respect to say that to my teacher when I was that age.  And all of this because they were asked to graph some data... which took nearly all of the 90 minutes to do, and do poorly at that.  Not that I told them that last part, but sheesh, look at those graphs-- do they look like work products that should have taken an hour to produce?!?  Notice there isn't a verbal conclusion or a particle diagram on any of them.  Let me just say there was supposed to be each of those as well.

I'm scared for the lab reports.  They are not going to be good.

Today really got me thinking about another teacher from my modeling workshop.  She mentioned that a constant problem she has with "inquiry" type labs, is that the students mess up, take away the wrong idea, and don't care enough to change their thinking.  That's very much what I saw with my students today.  I asked me students how they thought their graphs were going to look-- most said heating ice would be a straight increase, cooling the lauric acid would be a straight decrease.  After they (finally) plotted the data, I asked if that's what they saw.  Yup, they told me.  I asked about the flat areas and the zigzags-- it must have been the hot plate.  Or *maybe* it was human error.  They don't care, the line went up at a point, so they were all correct in their minds.

Can I just get a do-over on this semester?  I think if I had to do it all over again, I'd start WAY easier on this group and build up a better relationship with them.  I set the bar high and was hard on these students from the start, and they have now shut down on me.

Unit 3 Reflections: Icy Hot Lab

Snow days.  Don't get me wrong, I love them... but they sure are making it hard to get through everything before the EOC.  The EOC date does not change no matter how many days we are out.  Yesterday was another snow day.  We picked up today with the Icy Hot Lab, and had to cram it into one day.

I haven't gotten to begin this unit as I would have liked with all the interruptions.  Wednesday I was missing a large portion of my classes due to paperwork for the ACT.  All we really got through was the Energy Reading Study Guide.  We didn't even have enough time to discuss the reading and study guide in class, so I had no idea how much understanding they had of energy.  Not surprisingly, my thinking-phobic, non-conceptual students love assignments where they just have to hunt and peck for the answers.  It was the best "work" I've seen out of them this year.

Today, I put some of the main points from the reading into a PowerPoint-- because I feel like this concept of "energy accounts" is going to be difficult for them.  Or maybe it's just difficult for me.  Anyway, I wanted to try to drive home the idea more before they have to apply it to a graph.

In a perfect world, I would have done the Icy Hot Lab over two days.  In that perfect world, we would have discussed and planned part 1 as a class.  We would have white-boarded and discussed our results from part 1 before going on to part 2.  But... that couldn't happen.  Monday, I have to proctor a state writing assessment.  Tuesday is when the juniors take the ACT.  So we crammed everything into today and will discuss results whenever we can.

I had to make some changes to this lab.  First, we used hot plates instead of ring stands/bunsen burners.  Our ring stands are pretty chintzy and our iron rings are ridiculously tiny-- supporting a beaker of boiling water over a bunsen burner was not going to happen safely.

The world's worst hot plates.  The entire casing gets hotter than the actual burner.

Secondly-- no Vernier.  :(  This is one case where I truly would have preferred collecting data and graphing with Vernier if it were available.  Instead, I had my students manually record the temperature every 15 seconds with digital thermometers.  I have no idea of 15 seconds was an appropriate time interval-- looking over the data, I'm not sure if we're going to see good curves.

There was no shortage of "teacher mistakes" with this lab.  For example, I forgot to have them make a hypothesis of how their curves will look.  Big oops!  I was just so worried we wouldn't have enough time to execute the lab that I completely forgot.  I also forgot to demonstrate how to take accurate temperature readings with my first class of the day.  I realized a couple minutes into the experiment that most groups were just letting the thermometer sit against the bottom of the beaker, giving them artificially high temperatures right from the start.  I was able to prevent this in my later class periods.

Another problem I noticed early in the day was students trying to fudge data-- they had an idea of what they thought should happen, so they kept trying to make the data match that idea (which is going to totally botch their curves).  I didn't get as much time to address this teachable moment as I would have liked, but I did make a point to tell all students to record what the data says even if they believe it may be incorrect.

When it came to the freezing of lauric acid part, the teacher mistakes were still in full force.  Again, I forgot to tell my students in my first class the importance of keeping the lauric acid hot before you begin.  Most of them grabbed the sample and let it sit a few minutes while they got organized.  Their samples were well under 50C when they began recording temperatures, giving very linear data.  By the time I noticed this, the groups were so far into the data recording that there wasn't time to start over.

Test tube of lauric acid cooling and freezing as it sits in a beaker of cold tap water

I just hope we get usable data out of this experiment.  I don't want to create/reinforce existing misconceptions.  Also, students will be writing their first lab report over this lab and I don't want it to be harder than it needs to be.  If the data is erratic, they are going to struggle with their conclusions and questions.

Did someone order a mid-winter vacation?

We were out for, count 'em, ELEVEN days in a row thanks to inclement weather.  For President's Day weekend, the students were supposed to have a 4 day weekend.  Staff was supposed to have an inservice day and parent/teacher conferences on Monday and Tuesday.  What we had instead was a huge snow and ice storm on Sunday night.  The storm was followed by a blast of unseasonably cold arctic air which stayed in place for over a week.  Here in the south, we don't have the resources to remove snow-- it usually just melts the same day.  So everyone was just forced to stay inside and wait for it to melt... and we kept waiting... and waiting... and waiting...

Eleven days later, we're back in school.  On Friday the 13th, students took their Unit 2 test.  I barely made any alterations to the test in the curriculum-- I think I added 2 EOC practice questions, a handful of temp and pressure conversions, and made one of the more difficult problems extra credit.  Results were much better than the Unit 1 test.  Lots of As and Bs and Cs and only a few Fs in each class (although I still have a boatload of students to make it up who were absent last Friday).  I actually had a student tell me today that PVTn problems are her favorite thing she has EVER done in science class.  Seriously?  Even I think that's a little sad.  But hey, I'm happy to finally have some level of engagement in chemistry.

Students have interruptions galore over the next few days, plus there's more snow in the forecast.  As a result, I'm greatly abbreviating Unit 3.  My goals are for the students to understand phase changes and heating/cooling curves, and I'd like to attempt the energy bar charts and a few heat problems, but only if there is time.  Today there was a lot of catch up to do after the long break, so we eased in with the Eureka video on Heat & Temperature and did the Energy & Kinetic Molecular Theory reading/study guide.  Tomorrow-- Icy Hot!

Unit 2 Reflections: Worksheet 3 PVTn Problems

My students... bless their hearts... grr...

Graffiti is beginning to appear on the back of my white boards.  It's mostly your typical, teenage stuff- doodles, smiley faces, although one board had a curse word in marker.  I did not have this problem AT ALL last semester.  I am NOT okay with this.  I'm 99% sure it is happening during our board meetings when they are holding up their boards, and specifically, I'm also 99% sure it's happening in my last class of the day.  In that class, I already catch them trying to hide behind their boards and text, read, sleep...  Instead of addressing the class about the graffiti, I think I'm just going to say from here on out the students need to prop them up at the front of the room.  On a related note, at our workshop, one experienced modeler mentioned that he has hooks hanging from his ceiling to hang the white boards-- if I ever get my own classroom, I'd love to do that.

Anyway- PVTn problems.  I mentioned in my last post, I had zero interest in deploying the "factor" arrow method for solving these problems.  Maybe someday I will change my thinking, but I personally do not see how that is a benefit for them.  Especially not when my students are given the combined gas law on their EOC equation sheet.

I do think the PTVn charts are helpful.  It keeps the students organized, and drawing an arrow for the "effect" helps maintain a connection between their conceptual understanding of particles and the math.

A sample of the PTVn charts on the first page of worksheet 3

I do not think worksheet 3 alone was enough practice and assessment.  In a perfect world, we would have more time to spend on this.  I planned poorly-- I planned for the test tomorrow, thinking we'd complete and check worksheet 3 yesterday.  We didn't check worksheet 3 until today, which cut into out review time.  But we have a 4 day weekend for President's Day/in-service, so delaying the test any longer won't be to our advantage.

Also, I think worksheet 3 is a *bit* overwhelming for low-level standard chemistry students.  There were too many different pressure units right off the bat, including some "minor" conversions.  And by problem #3, they are throwing the STP in there.  I would have liked to have built the students' confidence up with some more straight forward problems before I start switching units or worrying about STP.  If I have such low-performing students next year, I think I will add several easier problems at the beginning.  Also, the problems are boring as all get out.  I'd like to put some "real life" spin on these calculations.

But... after the kid's initial FREAK OUT at having to do some big time algebra with lots of different variables, they didn't seem to have an issue with solving the problems.  I'm curious to see how they handle them on the test tomorrow.

Unit 2 Reflections: PVTn Labs

It's no fail-- my students always surprise me.  Sometimes for the better, sometimes for the worse...

I was having some trepidation about how seriously I should pursue calculating the pressure in a manometer flask like so:

It's not a state standard, so I was going to play it by ear as the students completed Worksheet 2.  If they seemed to understand the concept quickly, I'd have them do those problems.  If not, I wasn't going to fight the battle.  Go figure, they mastered the concept in about 30 seconds.

Overall, they did really well with Worksheet 2.  I would say 85% of the class was even successful at the pressure unit conversions at the end with minimal help from me, and I didn't even tell them it was coming.  Granted a good portion of my students still freeze up like a deer in headlights when they see a conversion, but they can do it with some goading.

We ended yesterday with a Boyles Law lab.  The AMTA lesson plans have students performing 3 labs with Vernier equipment:  P & V, P & n, and P & T.  We don't have Vernier equipment at my school, however I personally have a single LabQuest and probes of my own.  I have mixed feelings about having students do too many Vernier labs, regardless of having the equipment or not.  I feel the students often are intimated by the equipment and software, which causes them to miss the entire point of the lab.  At the same time, I've watched many college students continue to struggle with the Vernier labs.  It would be nice to give my students the exposure now so they're more comfortable with Vernier in college.  I don't think there is a "best" answer when it comes to using Vernier with standard high school chemistry students.

Anyways...

My compromise was for students to do a simple Boyles Law lab using pipets and textbooks that I found on Flinn's website:




Then for Avogadro's and Gay-Lussac's Laws, my plan was to use the Vernier equipment and demonstrate the lab the students were supposed to do from the curriculum.

The Boyles Law lab went pretty well-- it was quick and straight forward.  My first two classes of the day figured out the relationship easily for the most part. Most of their boards looked something like this:

By the end of the day, I found there were more and more student procedural mistakes.  The most common was measuring the length of the water instead of the air, giving them an incorrect graph (this one was doubly incorrect):

I was bummed about their verbal conclusion.  And confused about their particle diagram.

The mathematical expression was really hard for them on this one.  I've found here most students just don't understand inverse relationships.  I showed them the concept of P=1/V, but I'm not sure how many took anything away from the discussion.

The Vernier demos were a huge flop.  The kids were bored to tears.  They didn't understand what I was doing, they just blindly copied the graphs on the screen into their lab notebook.  Seriously, there was zero advantage to pulling out the Vernier equipment for a demonstration in this instance.  I might as well have just talked at them for half the period.

What was most helpful, again, was the PHET simulation.

We also did a KMT reading out of the textbook, or tried to.  I wanted them to read thoroughly and write, but we only had about 10 minutes left at the end of the class to do the activity.  It became more of a "scan for the answer" activity, which I hate.

Tomorrow we will tackle PVTn problems using the combined gas law.  While I plan on using the PVTn charts, I'm not teaching the factor/train-track method they showed us in our modeling workshop.  Not happening.  I'd rather the students be able to plug and chug into the equation that they will receive on the back of their periodic table when they take the EOC.