Biology Models: The Great Blood Vessel Challenge–Hands-On Activity for Your Students

Materials needed for a reusable class set:
1 standard garden hose
1 soaker hose
1 discharge hose (find in pool supply stores)

This is an easy way to have students carefully consider the characteristics of blood vessels. To set it up, you will need three hoses (or lengths of hose) of three different types: a simple garden hose with fairly thick walls (red?), a soaker hose with mesh walls, and a discharge hose (blue?) such as is used to drain the water from swimming pools. The latter can be ordered from a pool supply company. It will flatten when not full of liquid.

Students use common hoses to model blood vessels

Directions:  Simply cut the hoses in lengths of 12 to 18 inches.  Each student or small group is then given one of each type of hose. They are asked to decide which best represents a capillary, vein, or artery. There is not one right answer, although some choices may seem more appropriate than others. Students must consider the properties of each type of blood vessel and make reasoned decisions regarding their choices, citing characteristics to back up their reasoning. It might be helpful to allow them to take the hoses to the sink and run water through them.

Background Information:

Arteries are thick-walled vessels that carry oxygenated blood on its journey away from the heart. (Exception: the pulmonary arteries also carry blood away from the heart, but it is deoxygenated blood on its way to the lungs where oxygen is added.) It is helpful to remember that arteries always carry blood away from the heart, Arteries Always Away. Arterial walls are composed of three tissue layers called the tunica interna, the innermost layer which includes the epithelial lining, tunica media in the middle, and tunica externa, the outer layer. The arterial walls contain more smooth muscle and elastic fibers than do the walls of the veins. This makes arterial walls thicker and more elastic, so they retain their circular shape in cross-section, even when emptied of blood on the commercially prepared slides your students may view. The walls are thicker than the walls of veins and more contractile. Blood pressure in the arteries is high and pulses as the heart beats. The greater elasticity of the walls allows them to spring back from pressure. Their greater contractility allows arteries to constrict or dilate to control blood flow to areas of the body. No valves are present.

Veins are vessels that carry deoxygenated blood on its return trip to the heart. (Exception: the pulmonary veins also carry blood back to the heart, but it is oxygenated blood returning to the heart from the lungs.) Veins are composed of three layers as are the arteries, but with less smooth muscle and elastic fibers. In a tissue sample such as those on commercially prepared slides, the emptied veins may collapse and flatten. Reduced connective tissue content in the venous walls allows the veins to lose their round shape readily when emptied. The blood in the veins is under lower pressure since it is farther removed from the pumping action of the heart. Since the blood pressure is lower and the journey through the veins is mostly against the pull of gravity, extra help comes in the form of valves present inside the veins. Contraction of skeletal muscles surrounding the veins also helps to push the blood back to the heart.

Capillaries are very thin-walled vessels with a very small diameter. Some are only 4 microns across. (Compare this to the diameter of the red blood cell: 8 microns!) They are the site of gas exchange and chemical exchange between the blood and the body’s cells. The capillary walls are only one cell thick, being composed simply of epithelium, and oxygen and carbon dioxide can pass through them readily. They make up for their small diameter by being extremely plentiful, existing in capillary beds in all tissues of the body except epithelial tissue.

Blood vessel illustration by National Cancer Institute, National Institutes of Health – http://training.seer.cancer.gov/anatomy/cardiovascular/blood/classification.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=45154160

 

Biology Models: Consider the Red Blood Cell

It was a pretty good lecture, as lectures go:  brief and to the point, with interesting subject matter– the red blood cell!  All other cells in the body depend on it to bring that life-giving substance, oxygen.  It’s tough and stream-lined to perform its function–zipping through the blood vessels with its payload, bumping into the vessel walls and other blood cells, stacking into rouleaux which reduce wear and tear.  Early on it loses its nucleus and organelles, including mitochondria, so it can transport oxygen with maximum efficiency, traveling by the bulk flow of the blood.  I described its width–8 microns–and the fact that it can fold to fit through capillaries that are only 4 microns in diameter.  A lovely little cell, admirable in every way!

And the next day the class remembered nothing!  I could almost believe we were viewing each other from alternate universes, with no sound and no meaning bridging the gap in between.  Over the summer I thought about it a lot, and finally I went shopping.  In a pet store I found a flexible rubber frisbee.  The fabric store yielded some stretchy red cotton knit and some batting to pad the edges.  Then I went home and sewed a red blood cell, a handsome bi-concave disc, flexible yet strong.

In time, I added to the one red blood cell: an ABO set plus a sickle cell.

In the new school year the day finally arrived when the lesson included blood cells.  This time I tossed the disc to a kid in the middle of the room, asking “What is this?”  They passed it around, looked at it, and came up with the answer.  “Why do you think so?”  “What characteristics do you notice?”  “How can this 8-micron-wide red blood cell fit through capillaries only 4 microns in diameter?”  “What could be the benefit of having no mitochondria?”  At this point I added five minutes worth of further information.  The next class meeting, the students could tell me a lot about red blood cells, without even checking their notes.  Over time that one red blood cell grew to a collection of four, with black and white buttons to represent blood type antigens, plus an appropriately shaped sickle cell.

My conclusion:  an object to hold in the hand, to observe, to bend, and even toss around the room, made quite a positive difference in kids’ receptiveness and retention!  Probably any teacher reading this has already reached this conclusion for her/himself, and I knew this too, even before the red blood cell epiphany.  However, after that I devised even more biology models, and I used them in a more determined and systematic way.  Using them in an introductory lecture, then having students explain key concepts using them, and finally, bringing them out for review prior to tests–this is a powerful strategy to enhance student understanding and recall.

So when and how could a teacher use manipulatives?

  1.   Introduce a topic:   Bring out your biology models to lead into a lecture.
    Question the students:  What do you observe?  What do you suppose it represents?  What is its function?  Comment on the surface area-to-volume ratio– is surface area increased by the way the object is shaped?  How would that affect its function?  How might it interact with what you studied before?
  2.  In your lecture:  Manipulate the biology model yourself as you discuss it.
  3.   Pose a mystery:  Hand out the model and have students examine it to find an answer.    Ex:  How does this red blood cell, 8 microns in diameter, pass through a capillary that’s only 4 microns wide?
  4.   Have students use the object to explain its function to the class.
  5.   For a powerful review:  Put your biology models out in stations with question cards for the students to use, answering  together as they move around the room.
  6. Comply with NGSS:  NGSS calls for use of models.  When there isn’t time for students to create their own, then bring out biology models you have made or purchased, and watch your students get engaged.

 

Six Cool Ideas to Help Teach, Learn, and Review

Are you seeking active learning strategies that will engage your students?  Do you want your students to have fun with life science?  Here are six great ideas, for teachers by teachers, for using our educational tools in teaching, learning, and review!

In Combination

Put several kits on the board at the same time and let the class figure out how they’re connected.  Different kit combinations that can be useful include:

  •  Macromolecules/Digestive and Respiratory/Enzymes (see the image below)
  •  Macromolecules/Enzymes/Protein Synthesis
  •  Cells/Cell Membrane/Photosynthesis
  •  Photosynthesis/Cellular Respiration
macromolecules_digestivesystem_enzymes
Pieces from several board kits are displayed at once to challenge the students. Change the enzyme name to lipase or amylase. Ask students to match the enzyme to its substrate and location.

Repeat to Remember

Leave a kit up for awhile so the kids can just handle the pieces and put them together over and over.  Handling and assembling the kits repeatedly can help students remember structures and understand processes in biology and life science.

Review/Use Stations to Engage Students

To review for a test, set up stations with our life science kits and have the kids work their way through the stations, assembling and explaining them to each other.  They’ll be more engaged in the review if it feels less like a lecture, and as they handle the pieces they will remember what they learned initially.  And you can also use our magnetic life science models as assessment tools in teaching life science and biology.

Emergent Properties Intro

The Levels of Organization Kit makes a particularly effective tool for student discovery and engagement.  Students will have some prior knowledge on this topic, and as they attempt to place the levels in order and match them to the pictures, those who are watching will be drawn in to help arrive at the correct sequence.  This makes a powerful introduction for a lecture on emergent properties and even for an overview of your course!

Not Enough Magnet-Receptive Board Space?

Improve your classroom setup with more board space!  Drop by a paint or hardware store and pick up magnetic paint.  This is water-based paint that is full of iron filings.  Two coats on a wall or cupboard doors will provide extra display space.  The paint can be given a top coat in a color of your choice.

The Coolest Idea of All!

Speak Easies kits save you time by helping to organize your lecture, by providing a quick review of your topic in the background information sheets (Board Kits), with suggestions for use, and with built-in activities in the Desk Kits.  Wouldn’t you like a little spare time?

 

 

Place-Based Learning: Restore a Watershed!

STRAW Student Restoring a Wetland
A smiling student hauls mulch for newly planted trees in a wetland restoration.   Photo courtesy of STRAW

When you’re looking for project-based learning that is rich and rewarding, having your class restore a creek or wetland can’t be beat!  Kids are out of doors, learning by doing, and benefiting their community and the environment.  Fresh air, physical exercise and teamwork make a powerful combination.  Plus at-risk students sometimes come alive at a restoration, experiencing the benefits of teamwork and performing real work that helps the environment.  Sometimes the unexpected happens:  the kids find a snake or lizard, tracks of a raccoon or even mountain lion scat!  One team dug up the champion of all root balls from an invasive Himalayan blackberry.  And once, working on a creek at a ranch,  the class was super excited as a calf was born in front of their eyes!

Elementary school students working together to restore a wetland
Students restoring a wetland–teams spread out to get the job done. Photo courtesy of STRAW

Many topics related to watersheds, creeks, and wetlands can be explored in the classroom, either before or after the restoration takes place.  You’ll find some suggestions at the end of this article.

But how do you get your class involved with a restoration of a creek or wetland?  Read on.

Of course, you can plan and carry out a restoration all on your own, though it’s a lot of work, and the expense for plants, tools, watering arrangements, etc. will certainly add up.  But here’s the valuable bit of information you should know:  there are many watershed groups around the country doing this kind of work.  Friends of the ___ River, Friends of the ___Bay, as well as other environmental NGO’s, local water agencies, and local departments of public works, may have restoration projects in the works or may be able to connect you with other groups that are involved.  And that could save you an enormous amount of work (and money), but still have your students restore a creek or wetland.

For the ten years since I retired from teaching biology,  I’ve worked with a watershed group north of San Francisco Bay called STRAW, Students and Teachers Restoring a Watershed, a project of Point Blue Conservation Science.  My classes— biology, physical science, and environmental studies— worked with this group before I left  the classroom, so I knew what they were all about and went to work for them eagerly.  STRAW began 23 years ago and performed its 500th restoration in 2015, having coordinated restorations involving many thousands of students, K-12, and having restored over 30 miles of creek banks and acres and acres of wetlands.  STRAW also has our team of dedicated retired educators who take related lessons into the classrooms.  Having repeatedly seen students restore creeks and wetlands and the impact on students and teachers, I can’t think of a more powerful project to benefit everyone!

So what kinds of classroom lessons make a smooth fit with restoration and have rich educational value?  Here are just a few:  water quality and testing, native plants and animals, food webs and energy flow, rain gardens, water-borne disease, population studies and estimating numbers, identification and classification, carbon sequestration, and sustainable water policy.  Plus another big one: positive ways of dealing with climate change!  Read about climate smart restoration here.

And here you can read one teacher’s comments after she had her students restore a creek with STRAW.  

Creek Restoration: Tony Plants a Tree!

deskWe know that place-based learning can make a positive difference in kids’ lives.  For example, restoring creeks can restore kids.  At-risk kids, kids with gang affiliations, kids with low self-esteem:  all of these can benefit from accomplishing the restoration of a creek.  But sometimes it doesn’t lead to a complete turnaround…

There he was—the kid who was placed in my sheltered biology class to wait out the two weeks till he could be transferred to the continuation high school. Well-groomed and fastidious, doused with aftershave, he walked in and put his head down on the desk as soon as he was assigned a seat. And there his head remained day after day. He was absolutely determined not to do a thing. The day arrived when the class went to the creek bordering the school to work on a restoration, removing some invasive plants and planting native trees, shrubs and forbs. “Tony” asked to stay in the classroom, but I refused— after all, no one else would stay behind. So he came along as we walked down to the creek. Proper planting techniques were demonstrated and tools were distributed. The work began. I brought Tony a shovel and led him to a spot that needed a tree. He balked, I insisted. His clothes would get dirty, but “Not to worry—it’s not muddy.” His hands would blister and get dirty; “You’re in luck, Pal—here’s some work gloves.” And finally Tony went to work. The class was there for an hour and a half, and Tony planted three trees, with a little help from a couple of classmates. As we walked back to class he had a little swagger in his step and was more animated than I had ever seen him.

I wish I could report that Tony turned the corner that day, but no. He kept his head on the desk the few remaining days till he transferred out. Still, he planted three trees, trees that are growing there even now. And I don’t know what that might have meant to Tony. Maybe the experience had some positive value for him. It certainly had positive value for the creek!

And it had a lot of value for the rest of the class. The students were proud of their work and supportive of their team members. They made a positive difference for the environment, their school, and their community. More to come about restoration in our next posting.

Waterborne Disease/ Poop Chronicles, Part Two

Waterborne Disease/ Poop Chronicles, Part Two

 

stopepidemicscreenshotThe cholera epidemic in London in 1854 was raging on, and Queen Victoria had called Dr. John Snow and commanded him to stop the epidemic.  But this seemed impossible, since no one at the time understood the germ theory of disease or how diseases spread.

Some strange ideas about how to avoid disease were floating around, as seen in this somewhat exaggerated newspaper cartoon.  We can all imagine how scary it must have been to be surrounded by an epidemic and not know how to protect yourself.screenshotstayinghealthy

But Dr. Snow did something unprecedented—he went into the area of the city where the epidemic was in progress, the neighborhoods around Broad Street, and he interviewed the survivors of the disease as well as the families of the deceased, to gather information about how the victims had lived, looking for clues.  [The students can be supplied with this map of London at the time.  Discuss with them the symbols on the map, being certain to discuss the pumps that were in use.  The picture at the end of this article may be helpful, since not many students have ever used such a pump, but if you show it before the class tries to figure out how to stop the epidemic, it’s a tip-off.]

screenshotbroadstreet

[At this point, the class can be supplied with information about the victims, in addition to the map, and asked to figure out how to stop the epidemic.  This activity is from Project Wet, a wonderful resource for many water-related lessons, and can be found at http://www.rivanna-stormwater.org/bacteria.pdf.  When students have figured out how to stop the disease and have discussed the additional question at the Rivanna Stormwater site, continue with the Poop Chronicles lecture.]

After figuring out that the disease was spread through the contaminated well water in the Broad Street pump, Dr. Snow told the authorities how to stop the epidemic:  “Remove the pump handle.”  Eventually the suggestion was carried out and the epidemic stopped.  It was found that “Patient 0”, the source of the disease, lived in a tenement house close to the Broad Street pump, and effluent from the tenement’s privy was leaking into the ground water and contaminating it.

Subsequently the Queen called in Sir Edwin Chadwick, who made some recommendations to improve the health of the people living in London.  He designed a house, intended for a single family to live in, which removed their pump at the greatest possible distance from their privy and also supplied more room as well as air circulation and natural light.

screenshotlondonsewersAnd eventually this plan was submitted to the Queen.  What does it show?  Sewer lines!  Even  so, when the sewers were put in, they simply drained the sewage to the river.  Sewage treatment plants did not come about till later.

 

screenshotwaterpump

[A good extension of this activity would be to investigate some other waterborne diseases (for example, polio virus, giardia, Salmonella typhus),  along with a few other contagious diseases.  Students could be given pictures of the pathogens that cause the diseases and asked to investigate the symptoms, causes and cures, in addition to prevention.  The students could also be given a picture of the body showing different organs and asked to match the pathogens to the organs they infect.  And finally, they could sort the pathogens according to which taxonomic kingdom each belongs to.

To emphasize the environmental aspects of waterborne disease, you might show students the form below, which shows a data table for a number of tests that, taken together, comprise a water quality index.  Note that one of the tests checks for the presence of coliform bacteria, a family of bacteria always found in sewage.]screenshotWQI

 

 

 

Exciting Cell Projects for Your Students

Cells and Cell Projects
To introduce the cell or for review, you can’t beat manipulatives! Pictures of organelles that can be placed on a picture of an “empty” cell, (just the membrane or membrane and cell wall with cytoplasm and maybe ribosomes) can be a very effective strategy to engage students.
Have students try these:

  • Assemble and compare the plant cell and the animal cell.
  • Pass out the organelles.  Call out the name of an organelle and have the student who holds it bring it to the board and explain its function before adding it to the cell.
  • Have students choose the relevant organelles and use them to explain and enact an overview of protein synthesis.

Cell Projects                                                                                                                                                             Cell models made of cake, cookies, Jello, legos, styrofoam, cardboard, cloth.     One student, a dedicated skater, even made his model using bits of hardware from an old skateboard, housed inside a small metal box that originally held skateboard bearings!  The key to the organelles was pasted inside the lid.  I ran into him in a cafe 15 years later, and he told me he still remembered that model!
So it seems that these projects are time well spent. But after retiring, I wondered. If the high school students have made cell models in middle school and a brief review is sufficient to bring it all back, or if you want to present your class with more of a challenge, then maybe it’s time to up the ante.
How about going beyond the generic cell model and asking /assigning students to create a model of a specific kind of cell? Many cells are fascinating in their own right. With around 200 cell types in the human body, there’s such a rich assortment to choose from! But some students might prefer some type of plant cell or even a single-celled organism. You’ll see some ideas on the next page.

Cell Project—High School Level                                                                                                                        Make a choice from the lists below for research and a presentation. Make a poster to help as you present. Differentiated Cells These cells are specialized cell types that perform special functions. General requirements and questions to consider: Compare and contrast the specific cell(s) you chose to the generic plant or animal cell studied in class. What important function does your cell perform for the organism it is part of? How does the structure of your cell relate to its function? Are any of your cell’s organelles absent or present in extremely large numbers? To what effect? How does your cell function to help maintain homeostasis? Explain. Give special attention to any interactions between cell pairs. Do the cell pairs act together to achieve balance for the organism they are part of? What might happen if the cells’ interaction gets out of balance? Do the cells help each other in some way?                                                                                                                                           Cell Choices:

  • a cardiac muscle cell
  • a striated muscle cell
  • osteocyte/osteoblast/osteoclast
  • neuron and glial cell
  • sperm cell and Sertoli cell
  • red blood cell and platelet
  • vessel element
  • sieve tube member/companion cell

Cell & Protein Choices:

  • adipose (fat) cell and leptin
  • plasma cell and antibodies
  • chief cell and pepsin
  • red blood cell and hemoglobin
  • alpha cell of the pancreas and glucagon
  • beta cell of the pancreas and insulin

In the Age of Technology, Is Touch Obsolete?

Thoughts on Hands-on Aids in Teaching

Clearly technology is marvelous! It connects us to all knowledge all the time. Push a button, and any question is answered. Every structure is pictured; every process is animated. So perhaps tactile learning and kinesthetic learning are now outmoded! But wait. Ask a child. Ask a parent. Ask a lover. Best of all, ask a teacher!

Photo: Baby exploring tree with touch
Babies arrive at birth with an already well-developed sense of touch that continues to inform their perceptions of the world throughout their lives. Above, a 4 1/2 month-old baby, touching the bark of a spruce tree.

Teachers know classrooms are still full of diverse learners. Multiple intelligences and many varied learning modalities still exist. Kids need to move, and they need to use manipulatives. They need the teaching strategies that address these diverse learning styles.   Holding an object in your hand is an intimate act, and it gives possession to the holder. It connects us to the object itself and to the concept it represents. Teachers know how vital it is!

And of course, there is brain research. Marcia Tate and Warren Phillips, writing in their excellent “Worksheets Don’t Grow Dendrites” series, list manipulatives, experiments, labs and models, as well as movement, as essential teaching strategies that address brain-based learning. Tate’s and Phillips’ books cite and quote research rationales from experts in the field. (You can watch Marcia Tate here)

Speaking of touch, many excellent manipulatives are out there. Let students handle a model of a five-pound chunk of human body fat (Life/Form), available at eNasco.com, and they won’t forget your discussion of lipid molecules! Get students at the board, assembling a lipid (triglyceride) molecule from Speak Easies’ Macromolecules Board Kit, holding the pieces and mulling over their placement and function, and the intimacy of touch will facilitate connection, understanding and retention!