Microscopy in Anatomy & Physiology - Central Nervous System Lesson

 Following up on my last post regarding microscopy as a teaching tool, I want to share with you some of the work my Anatomy and Physiology 2 students completed this semester with prepared slides of nervous system tissues - spinal cord and brain. Once students have successfully focused the microscope slides, I encourage them to use their cell phones to capture photographs of their views.  

Cerebellum - student cell
phone photograph 

Cerebellum - Student drawing 

    

With many years of experience, as the teacher, you are very familiar with the tissues and their appearances that your students are working with, and what to expect when you look at their drawings. I've seen several lovely drawings of water bubbles (wet mount slide preparations by students) or dust specks. A couple of years ago I would have asked the students to step aside and let me take a look through their scope to assess their focusing skills. During COVID, I did not check looking through the scopes as we were practicing distancing. (When students were done working, I had them use alcohol pads to wipe down the eyepieces and knobs) That's what makes the use of phone camera shots in the lab another good assessment tool.  In addition, you can zoom in on the photographs and see even more details. Plus the students will have a record of the slides that they can refer to and study from should you plan on a lab practical. 

For this lesson, I wanted the students to identify key features of the tissues under observation. I generated the lab sheet below with the instructions for coloring and labeling. Students had the list of vocabulary terms that needed to be labeled. 

Central Nervous System Microscopy Lab Sheet 
Student Work Sample 

Under the Microscope

 

Dandelion under the microscope
pollen grains visible

One of the most enjoyable skills for me to teach to students is the use of the microscope. It seems to garner the most student "wows" and "ah-ha" moments. Through lecture, textbook reading, and other activities we teach our students about cellular structure, have them label the parts, draw or sketch the organelles, model with clay or other materials, but seeing them up close and personal seems to make it real. 

To scrape the inside of your cheek and smear it on a slide, add a drop of stain and a coverslip and then look through the eyepiece and see a piece of you can have a major impact on a student. This photo was the result of a brain/mask break last fall. A walk around the track and a student's lovely gesture of plucking and presenting me with a dandelion blossom. When we returned to the lab, they continued to work on their Gram staining technique, and I made a wet mount slide. 

Photosynthesis and Cellular Respiration Foldable

Photosynthesis and Cellular Respiration
Side by Side Foldable cover

If it is one thing I want my biology students to remember when they leave my class is to understand the interconnectedness of the two major energy systems in living organisms - photosynthesis and cellular respiration. This is the circle of life (imagine the theme song from The Lion King playing here).

For this foldable, take a sheet of paper, fold almost in half in order to allow a little overhang to serve as the folding closure. Cut down the middle to form the two half flaps.

I have also done this assignment in interactive notebooks.

Inside of Foldable 

As you can see, they used their textbooks to draw the diagrams of the chloroplast and mitochondria including all labels. Inside they diagramed the Light Dependent and Light Independent processes of photosynthesis and the three stages of respiration - glycolysis, Krebs (Citric Acid) cycle, and electron transport chain. The last diagram is essentially the carbon cycle showing how plants (which carry out both functions) and animals are related. Plants capture energy from the sun in order to make ATP which provides the energy for the chemical reactions converting carbon dioxide and water into sugars. The plants can then use those sugars (more importantly for us humans who eat the plants) to carry out cellular respiration to make ATP to provide the energy for all of life's processes - growth, reproduction, movement, etc.

"And yes, I want you to use color!" - answer to most commonly asked student question

Density Column Lab

Egg Drop Density Column Lab

It was midterm season once again and I was looking for a new lab for my Chemistry students to complete for their practical portion of the exam. I went hunting for a lab that would incorporate prior knowledge and showcase the student's ability to follow a lab procedure with little to no instruction from me, utilize the measuring skills that we have worked on all semester, demonstrate their understanding of laboratory safety rules, and to work independently. I found the answer in The Egg Drop Lab.

Because of time constraints (a two hour exam period that included a written portion) I set up the lab stations to include four liquid samples (I chose dark corn syrup, dishwashing liquid, vegetable oil, and rubbing alcohol into which I added blue food coloring) in graduated cylinders and indicated the empty mass of the glassware. I randomly filled the cylinders with differing volumes and the students had to calculate the density and predict what would happen if they added the four liquids to a test tube. Then they built a column to test their predictions. The lab procedure then asks them to predict where in the column water would settle and then to test that prediction. The next step was to determine the density of an egg and predict where in a column it would end up when dropped in. To minimize the amount of material used, I built the column using the student's input. The results are shown here. In addition I colored water with red food color and added it to the column before dropping in the egg.

What was really nice about this lab is the author designed this for an Earth Science course so it was an opportunity for me to have my students see the connection between what they have learned in Chemistry as it applies to the other sciences.

Field Trip on the Nashua River

View of the Nashua River

The Nashua River was once one of the most polluted rivers in the US. Squirrels were able to cross upon the paper pulp discharged from several mills along the river's banks, not to mention the garbage from town dumps, farm run-off and raw sewage. Tests completed for water quality showed there to be no dissolved oxygen, the key indicator for life in a body of water. Then Marion Stoddart, began her campaign to reclaim the river for her children and the children of all the communities abutting the river. She wanted to see people fishing, swimming, and enjoying the river. It was an enormous undertaking for a housewife, but through shear determination and the help from many who believed in her, the state of Massachusetts was the first in the nation to enact a Clean Water Law which eventually led to the US government enacting a federal Clean Water Act.

Today the river is classified as a Class B river - fishable and swimmable. The community I teach in is part of the Nashua River Watershed and I felt it important for my Ecology class to learn about the history of this river and to enjoy the benefits of Marion Stoddart's hard work. Through the Nashua River Watershed Association you too can participate in their River Classroom programs. We spent a couple of delightful hours out on the water where all the students were able to experience the role of paddler, data collector, and citizen scientist. At the high school level the program focused on conducting water quality testing (nitrate, phosphate, dissolved oxygen, temperature, pH, turbidity) on the water and aquatic life studies on the shore line. This data will prove valuable as we will be able to carry out the same tests at our school site and compare the health of the pond at school to that of the river. We will also be conducting tests on soil quality at school, so this was an excellent introduction for my students.

In order to prepare for our trip, I read to my students Lynne Cherry's children's book A River Runs Wild. With its beautiful illustrations, this book tells the story of the Nashua River from the time of the first Native Americans who came to live along its banks to today. Even teenagers like story time in the classroom. We also watch the documentary The Work of a 1000, the story behind Stoddart's work.

Our first try at the river was a washout literally as the day was forecast with thunderstorms, but one week later we couldn't have asked for a nicer day. I can't say enough about the quality of our guides and their knowledge of the river, its history, and the wildlife that edged the water. We saw signs of beaver, otter, and two great blue herons flew overhead. The students all enjoyed themselves, but I had a wonderful day. It was an accomplishment for me to see my students outside of the classroom and outdoors experiencing Ecology first hand. 

Lesson on Endosymbiosis

We are wrapping up our unit on prokaryotes and today discussed the role of cyanobacteria in the environment. Current theory is that in our evolutionary history at one time cyanobacteria entered into a symbiotic relationship with another cell which eventually resulted in the first plant cells. Molecular data supports this theory of endosymbiosis for the origin of the chloroplast, as well as, mitochondria. In both cases these cellular components each have their own DNA encoding in proteins specific to these organelles.

The lesson included watching this video clip and then proceeding to carry out the lab that is described within it. The challenge is to try to get the photo down the body tube of the microscope. Some days I'm better at it than others.

Moss leaflet showing chloroplasts within the cells

Mix of cyanobacteria and algae

Love those Flinn Fax - Chromatography

Chromatography sample set up

Earlier this school year as I was planning out my lesson on matter for my science seminar class, along comes the Flinn Scientific -Flinn Fax flyer in my school mailbox. What perfect timing! I had planned on doing chromatography, a method for separating mixtures, and here is a nice new twist on the technique.



Sample set up

I started the students on day one with simply asking them to set up a test paper with all the different brands of pens that I had available. The following day I gave them designs to copy. They had to use their findings to determine which pens to use. Everyone was successful as you can see by the pictures below. In the future I might even use different solvents to see if they can get results that differ from those they got here (we used water as our solvent but I gave them both water soluble and non-soluble pens).

Chromatography samples running

 I am continually amazed by what activities students are most fascinated by. This one was a huge success. Many simply tried to make interesting patterns of their own.




Student Sample 1

I placed my samples in plastic bags so that they wouldn't get wet. You can see here the student's work to copy my example.  I will now have these samples to use again next year which will save me a lot of preparation time.

Student Sample 2

Included in this photo you can see the sample disks that the students had completed on day one which show the pigment patterns generated by each type of pen available for use.