I read an interesting thread on the NSTA biology listserv that suggested teaching mitosis with DNA structure/replication instead of with meiosis as it is usually paired.  The idea is that mitosis is asexual reproduction and thus conceptually separate from meiosis, which is the basis of sexual reproduction.  I'd chosen cloning as the context for teaching about mitosis, and my students had started a webquest using the Learn.Genetics Cloning module.  I collected them to gauge their progress, and ended up with three groups of those who were almost done, those about halfway, and those who had barely started.  I put a different stamp on the papers of those in each group, and this was how I divided the class.  (Amazingly, this was the first time I had tried grouping the class this way, and it made my giant class of 25--which doesn't seem that big until you consider I only have 24 seats--a lot more manageable.)

I set up three stations and gave them about 25 minutes at each one.

Station 1 - Finish the cloning webquest.
Station 2 - Online Onion Root Tips (also available in Spanish).  Students read about the 5 phases of mitosis and sort cells into the right phase to determine how much time is spent in each one.  I gave them an online quiz through Schoology at the end.  Our state assessment is very general about mitosis, but knowing the phases is important for understanding meiosis, which is in turn a conceptual underpinning of sexual reproduction and chromosomal inheritance.
Station 3 - Build a DNA Molecule on the computer, then using Twizzlers and colored marshmallows.  This was everyone's favorite, of course, and the takeaway was very simple: A with T, G with C. Make sure students refer to the base-pair letters rather than just the marshmallow colors.

Much cheaper than DNA modeling kits, and every student gets to have one.

So I meant to blog about this weeks ago, but between the great Snowpocalypse closing school for 3 days, parent-teacher conferences, and the general mayhem of life, I never got around to it.

1. Place a raw egg in vinegar and leave for 2-3 days so that the shell dissolves.  This is a good lab to start on Friday, let it sit over the weekend, and pick up again on Monday.  Be careful there are no cracks in the shell though, or you will end up with Humpty Dumpty!
   
   
2. Once the shell is gone, the egg will be held together by the outer and inner membranes.  It's very fragile at this point, so tell your kids to be really careful!  (Every semester I always have at least one group break theirs at this point, so it's not a bad idea to make a few extra.)  Mass the egg and record.
3. You can do the next part several ways.  In order to move more quickly, I have each group put their egg in a different solvent and predict what will happen.  You can also put the egg first in distilled water, then in salt water or some other hypertonic solvent.  In either case, mass the egg after letting it sit overnight in the solvent and compare it to the pre-solvent weight.
4. Discuss the movement of water based on concentration.  I've found that this is a really tricky concept for kids to grasp and explain articulately, and I myself had a ton of trouble understanding osmotic pressure until I thought of it in terms of water concentration.  I always tell them that diffusion is the movement from HIGH concentration to low concentration, and then I say that higher concentrated solutions are "HIGH"-pertonic and lower concentrated solutions are "hypo for low"-tonic.  (I've also found that I almost never speak in a normal voice during class, but who's keeping track?)

 
We put this egg in Gatorade and it came out a lovely orange color and did not change much in mass, which suggests that Gatorade is in fact isotonic with our cells.

I woke up this morning after sleeping for eight hours feeling just as tired as when I went to bed.  This was the first full week without delays, cancellations, or finals since before the new year, and it definitely felt like the longest week I'd had in a while.  I could have a called in for a sub and I think last semester I probably would have.  But I managed to talk myself out of the bad place, knowing that my students needed me and I was ready even though I didn't feel like it.

It turned out to be one of my best lessons yet.  First I did a Move It! poll, where students moved to different sides of the room to signify their agreement or disagreement with a statement, about the way we've been using the new computers.  Almost all of them like using the laptops to take notes, research, and manage their assignments, though everyone is at different places on the learning curve.  Then we played a game of I am/Who is with cell organelles.  I gave each student the card for the organelle they had done for their Facebook page, on the back of which was a description of another organelle.  I started by saying "I am the cytoskeleton.  Who is..." and described another organelle.  The student with that organelle stood up, read their identity, and the next question.  With a little nudging, we did make it all the way around!

Then we went on our tour of the school as a cell.  I had taped descriptions of different cell organelles to places in the school that had analogous functions, and charged students with the task of finding the next one.  They ate it up, especially some of my kids who aren't usually great with written work.  Two noted "frequent flyers" told me, "If we do stuff like this, I ain't ever skippin your class, Miss Duann!"  And though I was initially nervous about taking 20-some kids traipsing throughout the school, appointing a line leader and a caboose (yes, just like kindergarten!) helped keep everyone together, and then the thrill of the chase took care of the rest.  They had a notes sheet to fill in as we went along with the descriptions and analogies.

The best part, though, came after class had ended.  During lunch duty, I stopped to talk with a student I had last semester and told him that we had done the school as a cell activity.  His eyes brightened.  "Oh!  I remember that.  Is that when the office was like, the...the...the nucleus or something?"  At which point I did a fist pump and a supremely undignified little happy dance.

Resources
Cell Organelles I AM/WHO IS cards
The School as a Cell (with teacher key, student handout, descriptions)

Even though there were only three days between the end of first semester and the start of second, it almost felt like a brand new school year.  The orderliness of my desk has reached its semester high and will rapidly deteriorate from here...

More significantly, I have a brand new batch of students.  Admittedly, I was a little nervous about starting from scratch building relationships with new kids, but it was much less scary than the beginning of the year because several students had already said hi to me last week, and lots of my kiddos from last semester popped in yesterday too.  It was so much nicer to be surrounded by friendly and familiar faces!

Mugging with 3/4 on the last day of regular class

One of the teachers at my student teaching placement advised me to stay away from teacher's lounge gossip concerning students, and I definitely heard a lot of negative things about many of my new students before the semester started.  But I really wanted to give each one a clean slate because I believe that students--like all people--grow into your expectation of them, at least in part.  So I stuck with my plans for a student-developed code of classroom conduct, and intend to try my class officer system.  Ran out of time to introduce it with my 3/4 class, but my 8/9 students seemed interested in the idea and even suggested that it be for extra credit, which I'm okay with doing since it is extra work.  The irony is that if they fulfill all the requirements for being class officer in the first place, chances are they won't need extra credit.  But if it makes them feel better...

Class Officer Responsibilities

• Community: Take attendance every day and collect any tardy slips.
• Respect: Mark those who are not in their seats when the tardy bell rings and choose from the list of appropriate penalties.
• Effort: Keep track of who leaves the room using the hall pass or a nurse’s pass.
• Discipline: Update the assignment sheet with the day’s assignments.

Class Officer Qualifications

• Attendance: To qualify for class officer, a student must have been present in class for the past 5 consecutive days.
• Tardies: To qualify for class officer, a student must have no more than 1 class tardy in the past 10 days.
• Detentions/Referrals: To qualify for class officer, a student must have no more than 1 detention during the current quarter and no office referrals from this class.
• Missing Assignments: To qualify for class officer, a student must have turned in all assignments due the previous week.

I also had a much better idea of how to start the semester with a bang than I did at the beginning of the year.  Instead of running through the syllabus first thing, I cut out instructions for building Legos and glued each step on a different index card, which I distributed as students came in the door.  When the bell rang, I dumped Legos on the desks and told them they had five minutes to take their first quiz--go!  Everyone scrambled to build their individual step first, then they gradually figured out that they had pieces of the same puzzles.  This gave me a chance to quickly scope out group dynamics: who are the class clowns, the chatterboxes, the cheerleaders (not in the stereotypical sense but those who lift the class's spirits), the omniscient observers, etc.  I also had them write their names on popsicle sticks which I want to use during discussions this semester since the class sizes are bigger.  We talked about how the Lego activity modeled the scientific process and the kids came up with a pretty decent list after some prompting: observation, inference, prediction, testing, collaboration, and tentativeness.  Then we went over class expectations and I had the kids start working on their own definition of CRED.

Here's hoping for a happy new semester!

P.S. Shouldn't we get double the experience for teaching two "yearlong" courses in one year??