Unit 4 Reflections: Cellular Respiration Continued

Cellular Respiration-- not one of the most interesting things we get to teach as biology teachers.  I mean honestly, raise your hand if you actually care about the Krebs Cycle?  I sure don't.  And I've never totally understood why or how it's important for the state to test students on whether more ATP is produced in Glycolysis or Oxidative Phosphorylation.  But I digress...

We held our board meetings on yesterday's activities.  Here's how I set it up:

Yesterday, I had written a generic definition of "cellular respiration" on the board that they copied down between activities.  I didn't talk about it at all, I just told them that they were modeling "cellular respiration" with the ball and stick models.

Today, I asked them to refer back to that definition and create a white board with a verbal, mathematical, and diagram explanation of that definition of cellular respiration using evidence from the two lab activities.  They were confused and stumped, but surprisingly game and receptive to the challenge.

Prior to WBing, we had recapped about the "ingredients" in each of the balloons, and even hypothesized a little about each of their role in inflation of the balloon.  They had some really interesting theories they were all sure of-- the warm water caused the molecules in the balloon to move faster, causing expansion of the balloon.  The warm water dissolved the sugar faster so it could "react" with the yeast.  The yeast was a catalyst.  The yeast produced oxygen.  I just kept telling everyone those were interesting theories.

Most groups used the chemical equation for mathematical (I kinda tipped them off on that), and diagrams of the balloons or models were easy enough-- but they were stumped on the verbal.

In each class, I spend a lot of time with about 50% of the groups firing questions at them, and basically ignored the other groups.  I tried to focus on the "weaker" and more uncertain groups.  They all had the same questions:  "We don't know what you want us to do.  These labs had nothing to do with each other."

In my rapid firing, we focused on the glucose and the chemical equation.  Glucose was one of the reactants in the model of cellular respiration.  Was glucose involved in the balloon lab at all?  (Yes, it could be derived from the sugar)  Was anything else in the chemical equation also found in the balloons?  Where did the oxygen come from?  What evidence did you have CO2 may have been produced?  Does it seem plausible that this reaction could have happened in the balloon?  So if I leave sugar sitting on the counter, it will turn in to CO2 and water, right?  (Umm... no...)  Then why did the balloon inflate?  What else was in the balloon?  Re-read that definition-- why did we add the yeast?  What did we discuss about yeast earlier?

And then about that time, each group had the most rewarding OH MY GOD I GET IT light bulb moments.  :) :) :) :)

My only regret is that these groups were SO excited they "got it" and while many of their peers still didn't... and they WANTED to blurt it out in the board meetings.  The groups I spent time with were waving their hands in the air the entire board meeting, wanting to talk... and I reeeeeally wanted to let them show off their new found knowledge.  But... I also wanted everyone else to have that same epiphany.

We then did a terribly boring textbook "active reading" session about ATP.  Great way to cap that good discussion, huh?  But there was a reason.  On Monday, we had a district teacher inservice with a speaker who I will not name.  He was not one of the better educational speakers I have ever heard.  While he made some good points, overall I thought he was extremely antiquated and out of touch with today's students and schools.  His big emphasis was on more reading and writing-- less doing, more reading, writing, and note-taking.  Kids today aren't college prepared because they can't read textbooks and they can't write papers (I do agree with that part).  One of his criticisms of science teachers was that we "do" too much and pride ourselves on not even using a textbook (um, guilty).  I disagree with him that you should only read and write about science, but I do think I am doing my students a disservice if they never have to trudge through a science textbook at least a few times.  While we do read in class, our reading is usually article-based.  The speaker gave me a good reminder to step it up with the textbooks.  Reading about ATP was a perfect opportunity-- I can think of no topic more dull to practice reading dull stuff.

Each student received a photocopy of the 4 pages out of the text on ATP and highlighters.  We read the first few paragraphs together and discussed how to identify the important points... then I set them free with a guiding question (what provides energy for the cell) and told them to keep highlighting what seemed important.  Afterwards, they were to write a paragraph reflection of the reading that answered the guiding question.  We discussed our paragraphs afterwards, which was extremely insightful.  While many students did fine and wrote great summaries, here is a direct quote from a bright honors student with a 98 class average:  "I didn't understand a single thing I read."  Hmmm.  While I don't think we will be reading the textbook every day, I definitely do think I need to throw it in more frequently.

Unit 4 Reflections: Macromolecules and Cellular Respiration

...and we're back from our lovely 10 day fall break today.  And jumped right in with cellular respiration.

I've had to add a lot to unit 4.  Not only did I toss in all the ecology standards, but I also needed to cover the biological macromolecules in more depth than the AMTA lesson plan suggested.

The AMTA lesson plan has students researching proteins, carbohydrates, and lipids on their own with a few guiding questions, then jumping in to comparative dissections.  My state EOC exam tests pretty darn heavily on proteins, carbohydrates, and lipids-- especially the structures and how to determine their presence in the laboratory.  Plus, our biology teachers here usually save our dissection for the last days of class after the EOC exam, since dissection and internal anatomy are not tested.  So, I ended up skipping the dissections (for now) and spending more time on the macromolecules.

Having the students research the macromolecules with guiding questions was futile.  First of all, when given the option of textbook or Google, students always go to Google.  I don't think that is necessarily a bad thing, as textbooks are becoming utilized less and less, even at the collegiate level.  But... as sophomores in high school, students can be easily led astray by misinformation online.  Especially on a topic like this, which is loaded with intimidating new vocabulary like "monosaccharide" or "polypeptide."  The whiteboard results I got, to put it simply, were really bad.  I still think it was a good activity, but I will definitely limit them to the textbook next time to avoid wasting nearly an entire class period.  Instead of dissections, we then went to the lab to practice testing for macromolecules.

Sudan IV testing for lipids

The AMTA curriculum kicks off cellular respiration with a yeast lab using Vernier Probes to measure % O2 and CO2.  The total amount of Vernier equipment my school owns:  0.  We got nothin'.  So it was back to the drawing board again.

What I decided to do was combine a yeast balloon lab with the next activity in the lesson plan, which is modeling cellular respiration with ball and stick models.  First, students created balloons with yeast and differing amounts of warm water, sugar, and air:

They measure initial diameter, set their balloons aside, while I briefly introduced them to the term "cellular respiration."  They were instructed to make a model of a glucose molecule and 6 diatomic oxygen molecules:

A glucose and a pile of O2 - not bad for students who have never taken chemistry, let alone organic chemistry. I wasn't going to split hairs on the position of the bonds in the glucose at this point. Maybe I should have.

They were then told a chemical reaction occurred between the molecules and they needed to create two new molecules.  I asked them to think about waste products, respiration, and had to prod some groups on ideas... but all of them eventually came up with CO2 and H2O.  They were then challenged to figure out how many CO2 and H2O molecules this reaction would create.  Once they were complete, they had to create an equation for cellular respiration.

Then we revisited our balloons and determined change in diameter.

We didn't get much time to discuss or create a consensus.  My plan tomorrow is to hold a board meeting with a verbal, mathematical, and diagrammatic representation of cellular respiration based on the results of the two activities.  And I guess I'll see what I get!

Unit 4-- An ecological detour

When I did my cursory review of the biology modeling curriculum before the start of the school year, I somehow neglected to notice the utter lack of ecology included.  I guess I assumed when I saw food chains/food webs that the curriculum would somehow address ecology and interdependence in that section.  Well, you know what happens when you ASS-ume...

I believe something like 18% of my state's end of course exam is on ecology and interdependence, including human effects on ecosystems, carrying capacities, and succession.  Not to mention it's its own entire section in my state standards.  And uh, none of this stuff is anywhere in the curriculum as written.

So, the past few days have been "cram everything about ecology into a few days while pretending we're just learning about food chains."  Yay.  But it fit better here than anywhere upcoming.

I keep trying to relate everything back to energy, so it kind of makes sense with the unit.

Here's the cool part:  I'm reusing some of my previous ecology materials, but with a modeling spin.  And it seems to be working decently.  For example, I gave my students a what I think is an easy handout entitled "Deer:  Predation or Starvation" which has them analyzing and graphing the data of a standard wolf reintroduction scenario.  Oh, how my students moaned and complained about this activity last year!  The had so incredibly much trouble with manipulation and graphing of the data.

But this year, even my standard students got through it relatively uneventfully.  We used it for a segue into defining the term "carrying capacity," and they got it no problem.  I threw all sorts of carrying capacity scenarios out at them, and at least 85% of the students could predict and analyze what would happen.

Succession is another topic that we went through at warp speed, but I think they just might have gotten it.  (We haven't finished it yet with my standard class, which will be the true baseline for comparison)  We spent days on succession in previous years-- looking at pictures, drawing flipbooks, reading scenarios, etc.  Last year, I remember one of my brighter students telling me succession was the hardest thing in biology.

This year, I literally just cut up succession timeline pictures and put them in baggies-- I did one bag of pond succession and one bag of forest succession.  I told them to put each baggie of pictures in order and storyboard it on their whiteboard.  We discussed our observations and what we thought was happening, and defined the terms "ecological succession" and "climax community."  Then we discussed what might have caused the succession, divided the causes into categories, and voila!  We gave the categories the names primary succession and secondary succession.  And I sent them home with a Mount Saint Helens article for homework that will hopefully embed a few more related terms in their heads.  I mean, I would have loved to have done more, but we spent maybe 30 minutes on the topic.  From the discussion, the understanding seemed as good or better as compared to the years I've spent days on the topic!

It's the small battles, I suppose.

The downside:  we are seriously behind now.  Like, majorly, will-not-get-through-all-the-curriculum, what am I going to cut behind.  The only upside is that I'm not any more behind than I was this point last year, and my students did fine on the EOC...

Unit 4 Reflections: What is Energy and Energy in an Ecosystem- A Vital Commodity

Unit 3 tests are finally graded.  I was THRILLED to see a narrowing of the "great A/F divide" in my standard class.  Grades were higher than usual on the whole, and the number of failures was cut in half.  Some progress is better than no progress!

Verbal and diagrammatic representation of the energy in the "What is Energy" Lab

Unit 4 started off with a lab:  What is Energy?  Like many of the other activities, I found it took an excessive amount of time for a concept that the students were already pretty solid on.  There were 10 stations for groups to observe.  If I do it again, I think I may reduce the number of stations in half.  I found my students were familiar enough with the concept that energy cannot be created or destroyed and that it can transfer forms.

The teacher notes recommend reading the book, "Zoom" by Istvan Banyai before jumping into the next activity.  We didn't for two reasons:  1) We are really, really, really running short on time, but more importantly 2) I ordered the book last week off Amazon and it still hasn't arrived.  Maybe next time around.  My segue was just telling the students that we would be observing energy at the ecosystem, organism, and cellular levels.

I think the Energy in an Ecosystem- A Vital Commodity was great, except for one pesky detail.  In every single class, one of the trophic levels performed "better" than it should have despite me adjusting the numbers of each organism.  In both my honors classes, for some reason the dolphins acquired more energy than the cod:

Dolphins have more energy than the cod and the shrimp!

This has been easy enough to address through discussion, but I am still worried it is reinforcing a big misconception that the top organisms have the most energy!  I was trying to wait to stop the simulation until some dolphins died, but the problem was that my shrimp and cod were dying faster than the dolphins despite sufficient numbers of plankton.  If I waited for the dolphins to die, we would have had very little data.

In my standard class, who hasn't white-boarded yet, the cod were higher than the shrimp, which may make a huge mess when we graph.  I told them we might repeat the simulation tomorrow.

So we don't have that perfect graph to tip on it's side to make a nice half of an energy pyramid, because our data is off.

In the future, I might plan to repeat this simulation a few times until we get usable data.