Unit 7 Chemical Reactions - Rearranging Atoms

If you had spoken to me yesterday, you would have heard how proud I was of my students.  But today is not yesterday, and once again I'm slamming my head against the desk.

We spent Monday through Wednesday on nomenclature and chemical formulas of ionic and covalent (molecular) compounds.  It was a lot of direct teaching, and we completed Unit 6 Worksheets 3 and 4 as assessment.  They worked extremely hard on something I would consider pretty boring and they were showing a strong mastery.

Today, we took a quiz on nomenclature.  I didn't use the AMTA quiz, but rather copied question #10 straight off the AMTA Unit 6 test.  (For the sake of time, I'm combing these last units into one unit test so we have more days for instruction before the EOC) They had to identify formulas or names as ionic or covalent, then write the name and/or formula.

The grades... so horrible... oh my gosh.  I would have NEVER anticipated the grades being so terrible based off what the students produced on worksheets 3 & 4 and our other in-class practice.  Most students couldn't even correctly identify the compounds as ionic or covalent, which we've been doing in class for DAYS.  So it looks like I'll be re-teaching the topic tomorrow.

The other plan for today was to begin Unit 7 by completing the Rearranging Atoms activity.  We do not have time for the nail lab, so I figured this would be a good way to introduce balancing equations.  The plan was to do the Describing Chemical Reactions lab tomorrow, since today's activity seemed very straight forward.  I foolishly assumed we'd be able to complete it in about 45 minutes and be balancing equations successfully for homework.  Ha!

First, the activity begins with 5 background questions that should be 100% review (ignore the copier line):

For some reason, these were the 5 most difficult questions in the world and my students SHUT DOWN instead of trying at all.  This caused me to just get ticked off, since none of these should have been a challenge.  There is zero excuse for them not to be able to answer any of these questions.  I basically let them have it and told them if they can't answer these 5 questions, not only have they shown me they aren't ready to go do chemical reactions in the lab tomorrow, but they don't even deserve to pass the course.  I was pissed.  There was a small standoff in just about every single one of my classes over these questions, and I refused to cave until they answered them and explained their answers.  After 14 weeks of chemistry, I should not have to spoon-feed my juniors answers to review questions that not only have been covered in my course, but were covered extensively in middle school and 9th grade physical science.  Maybe other teachers are content giving them the answers all the time, but the students should realize by now that they can't get away with that in my classroom.  Yet they still throw a temper tantrum any time I expect them to think (if you could even call those questions "thinking"- isn't describing like level 2 on Bloom's taxonomy?) and it's getting really old.

Anyways... after the background questions, students are to use atomic model kits to model the reactants given for a series of chemical reactions.  Students are to then build the products from the reactants.  If they don't have enough atoms or have left over atoms, they need to start over using additional reactants.

Once students find the correct ratio of reactants to products, they are to draw a particle diagram of the reactants and products and put the numbers of molecules of each in the blanks.

My first class just did not understand at all and we ran out of time.  My second class also did not understand at all... so I modeled how to do #1 and 2 at the front of the room.  They were still lost and we ran out of time.  By my third class of the day, some groups were sort of getting it, but many were still lost and surprise surprise, we ran out of time.

What was truly amazing to me was that I kept asking random students if they could guess what we were trying to do to the chemical equation.  Every single one of them said "no."  I figured someone would realize we were just balancing the equations, but nope.

Unit 7 Reflections: Worksheets Galore

Holy worksheets!  Unit 7 could be re-titled "the unit of a thousand exercises."  Or at least that's what it feels like.  Most of the units in the curriculum until this point have had less than five exercises. Unit 7 has nine!

Granted, they are pretty good worksheets, as far as worksheets go.  I really liked Exercise 3, which basically has students work through some of Mendel's pea plant data on their own and support Mendel's conclusions.  Challenging, but not too challenging.  Unit 7 doesn't bring up Mendel's name until well after we've discussed punnett squares.  I'm becoming a big fan of this pedagogical style-- students using what they've learned to support the findings of past influential scientists.  In my mind, it's far superior to the alternative of me rambling on about Mendel's laws, then trying to have the students apply them to real life.  The engagement level seems much higher-- students were much more willing to muddle through pea plant data when they already understood what should be going on.

The worksheets are broken up by some readings in The Cartoon Guide To Genetics by Larry Gonick and Mark Wheelis.

A few weeks ago, I ordered myself a copy of this from Barnes & Noble for $11.70... Barnes & Noble had the lowest total price when you included shipping.  Well, you get what you pay for.  My lovely book FINALLY arrived today ("arrives in 2-6 business days" yeah right).  While it looks like a nice enough book, I'm past the point of utilizing it this semester.  I'm looking forward to breaking it out next year.

Exercise 4 isn't actually a worksheet, but rather a genetic disorder research activity.  It also was a nice change of pace from the worksheets upon worksheets.  Groups are assigned one of six autosomal disorders:  Cystic Fibrosis, PKU, Tay Sachs, Huntington's, Polydactyly, and Sickle Cell Anemia.  The students in the group are to research the disorder and create a circle chart of the symptoms, genetic cause, treatment, and prognosis.

Exercise 4 Circle Chart

The students then presented this information to the class.  This was a nice, low key presentation that got everybody in the room talking and presenting, since I assigned each group member a "wedge" to research and present.  In my state standards "Checks for Understanding" section, it states that students should "Design an informational brochure to describe a human genetic disorder."  While not a brochure, I think this sufficed quite nicely, especially with limited time.

We then applied what we learned about genetic disorders to a way to track these disorders in a family (enter the pedigree chart).  We also introduced the concept of sex-linked.  I sent them home with the Hemophilia:  A Royal Disease reading and a couple questions.

Tomorrow is our last day of instruction for the SEMESTER.  Seriously.  Our state EOC exam will be administered next week.  Friday will be a review day, as well as whatever days next week that my students aren't missing for other subjects' EOC exams.

So tomorrow's plan is to apply a little more practice identifying autosomal vs. sex-linked in pedigree charts, briefly discuss dihybrid/polygenic crosses, and to bust through as many of exercises 5-9 as we can.  My early prediction is that we won't get through many...

Instead of the unit test, my students will just be taking a quiz on the unit due to lack of time.  This is the first time I have had to heavily modify one of the AMTA unit tests because I thought it was too rigorous for my students.  The test has a lot of differentiation between co-dominant and incomplete dominant.  While we covered those topics in the Potato Head Genetics activity, we just didn't have time to go into as much depth as I would have liked.  Instead, I substituted sample EOC questions on genetics, which lean more towards straight Mendelian crosses and pedigree charts.

Unit 7 "Alternate" Plan

The main plan for Unit 7 calls for 45+ days of growing pea plants prior to beginning the heredity unit.  That really isn't feasible for me at my school... although the real reason this idea was thrown out the window is because I didn't carefully read the Unit 7 lesson plan until about three weeks ago.  Oops.

Luckily, they give an alternate lesson plan for those of us without resources (or in my case, time) to execute the fast pea plant experiment.  It starts off with a simulation entitled "Potato Head Genetics."

Stock Mr. Potato Head photo stolen off the internet

We kicked off this activity on the Monday and Tuesday before Thanksgiving break.  Not exactly the best time to be starting something new, but we are pressed for time before the end of the semester.

In a perfect world, I would have 34 Mr. & Mrs. Potato Heads with a variety of different color "parts" to distribute to my students.  While they are only about $5 a piece, I wasn't about to spend nearly $200 of my own money on Potato Heads.  At the same time, I definitely wasn't going to walk into my department head's room with a P.O. for 34 Potato Heads, either.  So... back to the drawing board.  Quite literally in this case.  I bought one Mr. Potato Head from Walmart as a "model," but then had students draw their own.

The general idea of this lesson plan is we have to repopulate the Potato Head species by using a gamete bank to make test tube Potato Heads, then interbreed them to produce more offspring.  The goal is to introduce the concept of punnett squares, dominant/recessive alleles, incomplete dominance, co-dominance, multiple alleles, dihybrid crosses, etc

The lesson plan kept talking about this "gamete bank."  I was incredibly confused about how I was supposed to set this gamete bank up.  At a loss, I ended up spending tons of time making sets of popsicle sticks for each allele. Students randomly choose sticks out of baggies to determine the genotype of the test tube potato.  At the end of the day Tuesday, I realized I somehow missed this file in the lesson plans:

Gametes for the gamete bank.  These would have made my life easier.

As far as creating test tube potato zygotes, I tried doing it a few different ways in my classes.  In a smaller class, I split the room into boys and girls (since we had about equal numbers).  They randomly drew popsicle sticks to determine the genes carried by the male gamete and the female gamete.  Then we joined them together and drew the new individual.  I then reviewed the terms "phenotype," "genotype," and "allele" from unit 3 and we introduced new terms of "dominant" and "recessive."  We then discussed multiple alleles, incomplete dominance, co-dominance, homozygous, and heterozygous.

In my larger classes, I tried to have each lab group draw from the baggies to create a gamete, then join with a different group to make an offspring:

The product of fertilization

Next, in an attempt to introduce punnett squares and probability, students were to trace a gene through meiosis.  This is a great activity to show teachers just how well your students didn't learn meiosis.  Granted, we had to rush through Unit 6, but it became painfully apparent that my students didn't understand meiosis at all.  Sure, they could give rudimentary drawings and explanations of the steps, tell me about the 4 haploid gametes, tell me about crossing over... but attempting to trace a gene through meiosis proved impossible for most groups.  And quite frankly, there wasn't enough time to make them claw their ways to understanding.  As a result, punnett squares got put on hold and we jumped ahead to "mating" our potatos.

We did this activity on the Tuesday before Thanksgiving break, so as you can imagine, the students were off the wall.  "Do you realize you are the ONLY teacher in the ENTIRE school making us do work today?"  Haha, right...

Ideally, for mating, all students were supposed to start with similar genotypes from the gamete crosses.  Of course, since that went dreadfully, I ended up making quick "genotype" cards to distribute.   I did use the include data sheets, but I modified the activity again-- instead of doing multiple generations, students had to find a mate and create two offspring, all while listening to the sweet, sweet tunes of Billy Paul:

When we come back to class tomorrow, we're going to kick off punnett squares by discussing why our children don't look exactly like the parents, and then asking how could we predict the likelihood that a trait will be passed on...

I feel like I'm in constant "damage control" mode lately-- lessons keep not going as intended, and I have to figure out how to make something out of them the next day... sigh.  I'm really curious to see my students end of course exam scores after this semester... have they truly gotten anything out of this semester?  It's hard to tell some days...