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The "WOW" Factor of Nature!

How can you NOT love this?

This past week in my biology class was spent on a unit on classification and taxonomy.  This is one of my favorite topics to teach because the diversity of life on Earth is so incredible and amazing.  Just now, I am sitting at my kitchen table looking out over our large back yard.  The evidence of adaptation to our current environment astounds me.  I am making a list to share with my students on Monday:
1.   A hummingbird is at my feeder.  (Yes, in the deep south, we already have hummingbirds back from the winter.)  Its beak is perfectly adapted to extract the nectar from any flower.
2.   The bees are very active this morning, buzzing in and out of every flower in sight.  Flowering plants take advantage of the bee, and cover its body with pollen every time it lands on a flower.  What a perfect way to deliver a sperm cell to an egg cell of a flower a block away.
3.   The birds are singing like crazy this morning!  What a perfect way to find a mate and establish behavioral barriers between the species.

4.   I can see beetles who are perfectly camouflaged to blend in with their surroundings.
5.  The fruiting bodies of mushrooms are poking up from the ground to take advantage of the deluge of rain we have had this week.  Water will spread their spores to great distances.

6.  A great blue heron is wading at the edge of our shallow pond.  Its body is perfectly adapted for wading and grabbing up the small fishes it sees.

It is an amazing time of the year to be a science teacher.  Nature is packed full of examples that we can share with our students.  I certainly hope that my students come away from this unit with the same "awe" as I have when considering how natural selection has brought us to this point in Earth's history.  Every organism in our sight is adapted to this particular environment.  All we have to do is to look carefully at our surroundings and we will see a multitude of examples of adaptation.

My challenge to you is this:  When Spring hits your particular area of this beautiful earth, take a class period and go outside with your students.  Give them a magnifying glass.  Have them make a list of the living organisms they see, and have them describe how they are adapted to the environment.  Yes, some of them will be "off task" and some of them will misbehave, but some of them will get hooked on nature for life!   I teach high school students, and I am stunned each year at how few of them have ever planted a seed, taken a walk through the woods, hung a bird feeder at their home, thrown "helicopter" seeds into the air and watched them spin, watched a spider spin a web, the list could go on and on!

These children will be responsible for making decisions about our planet in just a short number of years. We better get them excited about nature.  We better make sure they understand how their actions impact our planet.  Our students are the future caretakers of this beautiful planet and there is not an "app" for that.  I hope that when they are adults we have taught them enough about science and nature that they can make informed decisions about how to take care of it.

Plant Transpiration - Great for All Ages!

I really enjoy teaching plants to my biology students.  I did this activity a few days ago on plant transpiration.  It is so simple, easy to set up, doesn't require any fancy lab equipment, and best of all, it is adaptable to all age groups, K - 12!

Transpiration is the loss of water from the leaves of a plant.  The leaves have small pores called stomata.  The stomata must open to allow carbon dioxide to enter the leaf for photosynthesis.  While the stomata are open, however, water vapor is lost from the leaf.  If too much water is lost from the leaf, the plant will lose turgor pressure and the plant will wilt.

Measuring transpiration from the leaf is a very simple thing!  I went to Wal Mart and bought one tray of Vincas (aka Periwinkles).  The one tray contained 6 plants.  Once back in my school lab, I placed plants in small (100mL) beakers.  I watered them thoroughly.  Since I wanted to measure the amount of water lost from the leaves, I took a plastic sandwich bag and wrapped it very tightly around the beaker, and around the stem of the plant.  It is necessary to insure that no water evaporates from the dirt itself.

1)  Place plant in beaker.
2)  Wrap beaker tightly around plant, and tightly around the stem.  Only the leaf should be sticking out of the plastic bag.

The only way water is getting out of this beaker is through the leaves of this plant!

3)  Find the initial mass of the entire set-up and write the mass on a piece of masking tape which is then placed on the beaker.

Now for the variables!  What factors will cause an increase or decrease in the rate of transpiration?  We decided to test the following factors:  (1) One plant will be placed in continuous light.  (2) One plant will be placed in front of a blowing fan.   (3) One plant will be placed inside a plastic bag that had previously been spritzed with water (high humidity inside the bag).  (4) The fourth plant will serve as a control.

This plant was placed in the beaker, the beaker was covered with a plastic bag, and the initial mass was written on the outside.
The plant was then placed under a lamp and left for 24 hours.

This plant was placed in front of a blowing fan for the same 24 hour period of time.

The inside of this bag was misted with water and the plant was then sealed inside the bag for 24 hours.  This simulates a high humidity environment.

This is the control.  The plant is still transpiring, but without the extra amount of light, without the fan, and without the added humidity.  A true control would be the absence of transpiration, but we decided to use a plant at normal room conditions as our control.

Let the plants sit for 24 hours (or longer if you want!).  Each plant is massed again after a 24 hour period of time.  Students will be amazed at how much water has been lost through the leaves.  The results should be as follows:

Plant in Light:  This plant loses a good amount of water.  The light causes the plant to continuously do photosynthesis.  This requires a lot of carbon dioxide, so the stomata stay open for a longer period of time to let in the carbon dioxide.  While the stomata are open, the plant will lose water.

Plant in front of fan:  The increased air movements across the surface of the leaf will cause a higher rate of evaporation from the plant.

Humidity:  Less water is lost from the plant when the humidity of the air surrounding the plant is high.

All masses should be compared to the control to see if the factor being tested causes an increase or decrease in the rate of transpiration.

Here are some ideas of how this might be used at different age levels:

Elementary:  It may be enough in the lower grades to just show that water is taken up by the roots and escapes from the leaf.  Students can be asked before the experiment to make predictions as to what they think the outcome will be.  They can form a hypothesis and go through the steps of the scientific method.

Middle Grades may add the following:  Have students calculate how much water is lost per minute in each plant.  Test an additional factor, such as complete darkness, or various temperatures.  Test different types of plants to see if the transpiration rate is the same in all types of plants.

High School Grades may add the following:  Remove the leaves and determine the surface area of each leaf.  Determine how much water is lost in a given amount of surface area.  Have students research the mechanisms of transpiration, such as cohesion, adhesion, capillary action, and transpiration pull.

These are just a few ideas that will allow this same simple concept to be used over multiple grade levels.  I hope you will give this a try in your classes.  I think many students have little experience in dealing with plants;  my students are always intrigued and interested in labs that involve plants.

I would love to read some comments if you have other ideas, or if you want to let me know how it worked for you.  Good luck...... and make science FUN!!!

Protein Synthesis Made Fun!

Sometimes when I teach  DNA, RNA, and protein synthesis, I feel like the only person in the room that "get's it" is me!    Many of my standard Biology I kids struggle with these concepts.  The whole idea of transcription and translation just leaves them looking like a deer in the headlights!

I developed this activity to help get the point across: Determining the Traits of a Mystery Organism Through Protein Synthesis

After teaching the basics of protein synthesis, use this activity to ensure that your students understand the concepts involved in transcription and translation.  I have found that my students understand the concept of protein synthesis much better after doing this activity.  And best of all, they get to color their mystery organism at the end.  It never ceases to amaze me how much high school students still love to color!  This activity is appropriate for grades 7 through 10.

Make Science Fun Again!

It is the time of year where teachers across the country have only one thing on their minds:    End of course standardized tests!!!  It doesn't matter what state you live in, or by what name they are called, they are the same.  They are standardized tests.  Every teacher feels the pressure.  It seems that nobody cares if you make your class fun and exciting....JUST GET GOOD TEST SCORES!!!
Please teachers, don't fall into the testing trap!  Keep your class fun, engaging, and exciting and the test scores will probably be better than ever!

This week I had my biology students do a DNA extraction.  It is such a simple little activity and I worried that my students might find it boring.  Boy, was I wrong!  They thought it was the neatest thing ever.  At the end, they all asked for a plastic bag so that they could take their DNA home with them.

You can click here to download my DNA Extraction Lab for free.  I hope that you will check it out.  It is simple, easy to set up and easy to clean up.  And best of all:  It does not require any fancy lab equipment.  Anyone can do it!  It is appropriate for middle and high school students, but I believe that even a 4th or 5th grader could do it.  (You just might not want to use my follow up questions for elementary, though.  But the lab procedure is simple!)

We extracted the DNA from wheat germ, which can be purchased at any grocery store in the health food section.  Here is a photo:

The "blob" being held up from the beaker is a huge amount of DNA!
I really hope that you will download this lab.  It is free!

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