Muscle Contraction Modeling

In Anatomy and Physiology class, we are discussing the Sliding Filament Theory of Muscle Contraction.  I gave short notes yesterday (until I could tell I was sounding like Charlie Brown's teacher... wah wah wah...) on the basics of muscle contraction.  In past years my students have had trouble with the idea that although the muscle shortens during a contraction, the individual thick and thin filaments don't change in length.

One thing I'd tried to combat this misconception was to show animations of the process.  I think this helped for some students, but for others the concept still wasn't clear.  This year I decided that in addition to notes, animations, and reading assignments, we would try a little physical model.

I drew up some images of the thin and thick filaments, laminated them on colored paper, and cut them out.  I have this available on my TPT store if you want to download the images and instructions - click here.

Students worked in groups to place the pieces on top of a white board and label the parts, taking a photo of their work.  They had to take two pictures, one of the contracted muscle fiber and one of the relaxed muscle.    The conversations I overheard while they were working were very meaningful, they were engaged and referring back to their readings and notes when discussing both the placement and labeling, and while answering the questions.

After they completed their work they answered 6 questions, bringing together their understanding from the activity today, their reading assignment, and the notes.

1.      When the muscle is contracting, what changes happen to the A band?  I band?  H zone?

2.      What are the purposes of the M line and Z disc?

3.      This is a very simplified model of the myofilaments.  What detail could we add to make it more accurate?

4.      Is there any situation where the thick and thin filaments no longer overlap?  Is there a situation where the thin and thick filaments are incapable of overlapping anymore?

5.      Describe the total length of the sarcomere as the muscle contracts.  Do the lengths of the individual filaments change?

6.      Thinking about what we discussed in class, how does the contraction happen chemically?  Draw a picture and describe the steps.

Hopefully this will drive home the idea that although the sarcomere shortens, the individual filaments do not change in length.

Malleability and Ductility of Metals

On Tuesday before Thanksgiving break, we did an activity on metallic bonding.  Monday we'd done a reading assignment from our textbook with a pre-reading activity and post reading video from YouTube where they identified and explained their "unknown" concepts from the reading.   I started Tuesday's class with a Power Point slide with three images, one of metal ions in the sea of delocalized electrons, one .gif with the metal ions being moved by a force, and a third with electrons flowing through the metal.

We then did two different experiments, one with a Metal Rolling Mill where they smash pennies, and another where they draw wires into smaller and smaller gauges.

In the first experiment we demonstrated malleability.  We have a few rolling mills bolted to 2'x1' plywood that we use C clamps to hold down to the counter.  Make sure that students are aware of the safety precautions, like keeping hands away from the rollers and making sure it's clamped tightly to the desk so it doesn't slip off.  Also, encourage students not to keep pushing if the handle is stuck; last year I had a student break the board that the mill is bolted to because she was forcing it too hard.  (Nobody was hurt, but the board had to be replaced.)

http://www.contenti.com/products/_enlarge.html?itemno=192-321&itemname=100mm+Flat+Rolling+Mill&section=rolling-mills

The Rolling Mills work like this

from http://en.wikipedia.org/wiki/File:Rolling.gif

We place the penny between the rollers and turn the handle to send it through.  The students should only turn the top knob a little each time and the penny will slowly (over 10+ trips through) stretch out and flatten.  If the kids are careful and the rollers are adjusted correctly, they can get the penny to stretch out several feet long.  The kids really get a big kick out of this and are always asking if they can smash other coins.  This year I had a student smash a token from the arcade.  This opens a conversation as to why we can't use this for things like wood or plastic.

My students sending their penny through the first time

After the lab, students diagram what happened to the metal atoms as the force was applied and answer questions about WHY metals are capable of being squashed like this, where an ionic crystal substance would shatter.

After the penny has been through many times.

Another talking point is why once the penny is smashed, it appears a silver color instead of copper.  Have them try both a pre and post 1982 penny to see the difference in the composition of metals.

http://www.progresstool.com/pd-circle-die-plate.cfm

The second experiment involves ductility of metals.  We use jewelry drawplates and take a larger thickness wire and pull it until it's much thinner.  The plates are relatively easy to understand, you just start with the number 1 and work your way up through each hole, pulling with the tongs.
  To get the wire to feed into the next smaller hole, you will need to file the first centimeter or so of the wire so it's thinner.  We used regular chemistry triangular files for this.  During this part it is VERY important to make sure students are wearing goggles to prevent metal dust/splinters from getting in their eyes.  I would also recommend holding the wire with the tongs while filing, as it's more sturdy and you're less likely to file your finger.  (From personal experience... ouch!)

The die plates must be secured in a

http://www.contenti.com/products/_enlarge.html?itemno=190-718&itemname=Drawtongs&section=drawplates

table top vise so that the students can pull the wire through as they walk away from the table.  I used the tall lab counters around the edge of my room and students could apply as much force as they wanted.  I think if it was attached to a regular desk they would just pull the desk around the room, as it does require a good amount of force.  Another technique to get it started is to grip a small amount of the wire and roll the tongs to the side, so it's pulled through with leverage rather than brute strength.


Students also diagram and discuss what is happening to the metal atoms as they turn a 2-3 inch piece of wire into one that's several feet long.


These are things that the students really seem to enjoy and I think it makes the concepts of malleability and ductility so much more real, rather than a definition on page 228.

Socratic Circle Anatomy Discussion

A technique that was suggested to me last year was the Socratic circle.  If you haven't heard of this, it's basically a class discussion technique that is very student centered, with teacher as occasional facilitator and the children leading the chat.  It is supposed to foster both literacy and content knowledge skills in a more authentic way because they're engaging in discussion and thought where they relate back to the original source that had the information.

We've already done several activities with bone at this point - we've learned and quizzed over compact and spongy bone (along with the femur dissection here), learned the differences between the axial and appendicular skeleton, bone shapes, and names for bone surface markings.  Thursday we did the Bone Forensics Lab mentioned here, where students determine differences between male and female skeletons and predicted height from femur and humerus length.  We've most recently read several articles or selections from books, and our culminating activity will be this Socratic circle discussion.

If you'd like to download full instructions for free - click here to visit my TPT store.

I have guidelines typed for the students, which we go over together as a class.

1. Be prepared for the discussion.  You can't be a successful participant unless you're familiar with the texts.
2. When you speak, address the other students, not the teacher.
3. Refer to the texts and mention where you found the information that supports your idea.
4. If you don't understand what another student means, ask a question.
4. It's okay to say "pass" if you have nothing to say.
5. Don't raise your hand, simply take turns speaking.

I also realize that since this is the first time many students have participated in this way, they may need some prompting.  I provide them with these prompts, but in the past I found they only needed them at first.  Once they got going they used their own ideas.

What did you mean by _____________?
I believe ________________ because ____________.
In the text I read ________________________.
I disagree with _____________ because __________.

The texts my students are reading for this discussion are

Written in Bone  by Sally M Walker (we chose Chapter 2 "Who Are You?")
Can We Predict Height? by Robert H Shmerling
Distribution of Lengths in the Normal Femur and Tibia in Korean Children from Three to Sixteen Years of Age by Jeong Hyun Ha

The reason I chose these texts is because they related to the topics we'd covered in class, they were interesting to read, and they represent three different difficultly levels.

The reading levels of the texts are grade 11, 14, and 17 respectively according to the Fleisch-Kincade method.  I think offering texts at different levels allows all students to participate regardless of ability, and offers enrichment for all students to be exposed to the harder texts.

When situating the room,  you can choose from a few ideas.  I'm planning on using one big circle, as my class has 18 students, so it's pretty small.  If I were using this technique with my class of 29, I would do two circles, one inside the other and have the students switch from inside to outside halfway through the discussion.  You can have students on the outside act as "notetakers" recording the ideas that are presented and noting things they'd like to add to the conversation.  You can also split the class into two discussion groups, but this offers some challenges to grading and facilitating.

When grading the conversation, you can mark the names of the students in the boxes, and then record their interactions with a code.  Some suggested marks are

RT = reference to text
O = expressed opinion
C = comment
RC = repeated another's comment
Q = asked a question

Obviously, you can tailor this to your needs, but it's a good starting point.  I took the discussion as a "classwork" grade, and required at least three comments/responses to earn full points.  You can ask for more or less comments per class depending on the size of your group.

Lastly, my discussion went quite smoothly in the past when I've written specific "Guiding Questions" for the students to discuss.  Like any conversation, sometimes it really flows and doesn't need any prompting, while other times the kids need a new topic to start the conversation again.  I aimed for two open ended questions per reading, and one finale question that allows students to discuss what they found most interesting or thought provoking in the texts.  I think seven quality questions will be enough to last the whole period.

The first time I tried this technique I was nervous... but I found the hardest part was NOT participating in the discussion myself!  The kids did a great job, and it's definitely worth a try.

Critical Thinking Skills

Last night I saw this posted on facebook, and I really enjoyed the ideas and the formatting.  Inspiring me to look for more activities that inspire deep thinking rather than just areas 1 and 2!

originally from http://www.flickr.com/photos/vblibrary/4576825411/sizes/l/in/pool-27724923@N00/

 I was looking for something for the skeleton in A&P because just memorizing the names of the bones gets tired after a while.  I think I'm going to use the ideas from these activities, modified for the bones that I have access to in my classroom.


Bone Forensics

Bones Can Tell Us More

After I modify the activity, I'll post results of what we did and how well it worked.

Beef Femur Dissection

This week in Anatomy & Physiology we are discussing bones.  We've read about bones, taken notes, and summarized what we know in graphic organizers.  If you'd like to download a copy of the instructions - click here.

This week's standard:

4.03 Describe the structure and functions of bone. Differentiate between spongy and compact bone.

I thought something new and fun would be to dissect a bone.  I haven't done this activity with my A&P class before, but wanted to give it a try.  I contacted a local butcher here in Central Ohio, who was wonderful enough to give me a great deal on some beef femur bones.  I got two femurs cut down the center to see the bone lengthwise, and 15 discs (about 1" thick) for students to dissect and observe under the dissecting microscope.

Beef femur with the head cut off - oops.

I would recommend showing the butcher a pic of what you wanted before s/he made the cuts, as they didn't understand that I wanted the femoral head attached and cut it off (but still were able to give it to me separately).





I had the students identify the following structures: diaphysis, epiphysis, epiphyseal line, metaphysis, articular cartilage, red marrow, yellow marrow, spongy bone, compact bone.  In addition, most were able to locate and identify skeletal muscle, tendon, and blood vessels.

Under the dissecting microscope, all students were able to observe the yellow marrow, and some were able to see some spongy bone with red marrow in it as well.

slice of bone for students to dissect, this student is removing some yellow marrow.

I think the most surprising thing that students found was that spongy bone didn't feel spongy.  I think they expected it to be soft and pliable, and it was a good experience for them to see how firm the lattice structure is where the red marrow is found.

I think next year I will show the butcher a pic of what I want before I order my bones, and for my students, I will make sure that I keep a sample of the spongy bone and red marrow (which is more difficult to remove than the yellow marrow) so that all students have a chance to view it under the microscope.

Overall, not a bad first try - and I think next year will be even better!

Electronegativity Trends 3D periodic table

Currently, we are working on periodic trends in Chemistry class.  We have already completed ionic and atomic radius, and this week we moved on to Ionization Energy and Electronegativity.

Ohio Model Curriculum states:

" Atomic theory and bonding must be used to explain trends in properties across periods or down columns including atomic radii, ionic radii, first ionization energies, electronegativities and whether the element is a solid or gas at room temperature."

The students have already read background information and summarized it to meet Common Core ELA standard

"Determine the central ideas or conclusions of a text; summarize complex concepts, processes, or information presented in a text by paraphrasing them in simpler but still accurate terms."

 I gave a short lecture on the two trends, and they've completed practice problems.  I was looking for something more hands on that would visually represent these trends, and a friend suggested this activity.


I think the students enjoyed the activity and hopefully it will enhance their understanding - we will see when we take the quiz on Tuesday!





First, we went over the instructions and the materials needed.
Per student: one straw, scissors, small ball of play-doh or clay, and a ruler with cm markings

I cut these apart before class started.  For a class of 28 you would need four sets.

 Teacher prep: make sure you've cut the dotted lines to provide one column for each student to build their model.  Then students will come together in a jigsaw to build the model from the work of 7 kids.












To make the larger group organization easier, I labeled the back of each purple column with A, B, C, etc. so the students would know which large group they were in, and the groups were randomly chosen.











The students cut the straws to the length determined by the electronegativity chart in their book.  Ex: 3.98 Paulings from the chart = 3.98 cm in the straw.

My students building their group of elements.

Then the students used the play-doh to stand the straws up.  Now, I read online you can use a large microwell plate for this instead, but I didn't have those, so we used the play clay as an improvisation.

One group of elements placed on the table when finished.

Once the students put their groups together on the empty periodic table map, they were able to see the representative elements all completed.

Finished Student Work

The students also answered questions about their work, leading them back to the ideas that Electronegativity increases across a period, and decreases as you move down a group.  We had a class discussion about the answers they had written, and the lesson was over.

From start to finish it took about 45 minutes in class.  Teacher prep time was probably 15-20 minutes to copy the pages, set out the scissors and rulers, and cut out the strips.  I also had some extra questions ready at the end to ask if the students finished early, or to use on an individual basis if there were students who moved really quickly and needed a little enrichment.


If you would like to download the questions and templates for this activity - click here to visit my TPT store. 

If you try this activity - comment below and let me know how it went!