Population Ecology Lab: Estimating Population Size

I have always found it difficult to find quality labs to use with my students when teaching my units on ecology. My school is on a busy city street, we have no access to a pond or woods, and only very limited access to grass in the school yard! Therefore, any labs we do in ecology have to be labs that can be carried out within the classroom or within the laboratory. One lab that works really well in my population ecology unit is "The Wild Bean Population."

In order to effectively study living organisms, scientists often need to know the size of a given population. A population is a group of organisms of the same species that live in the same general area. It is not reasonable to think that every individual in the population can be counted, and it is often difficult to get an accurate estimation of population size since organisms tend to hide, move around, etc. 

Population biologists have developed several methods for sampling a population. In this lab, you will use the sampling technique known as “the mark and recapture method” to estimate the size of a population of wild beans! This method involves "capturing" a number of individuals from a population, marking or tagging them, and then releasing them back into the wild.   

Anyone can do this lab since it uses very simple materials! All you need is dry white navy beans, dry red pinto beans, and a brown lunch sack.

The white beans represent the population of wild beans that lives within the brown paper sack. Students grab a handful of beans and remove them from the sack. This represents the initial capture of organisms. The white beans are counted, marked and returned to the sack. 

The easiest way to do this would be to have the students mark each bean with a Sharpie before returning it to the sack. I teach 5 biology classes, and did not want to have to throw away that many marked beans at the end of each class. My solution was to have the students replace the white beans from the initial capture with red beans. The red beans represent organisms that were initially captured and returned to their environment.

At a later time, a second capturing is conducted. Some of the organisms in the second recapture were previously marked while others in the second recapture will have no mark. If you know the following information: (1) The number of individuals initially marked, (2) the total number of individuals recaptured in the second group, and (3) the number of marked individuals in the second recapture, it is possible to make an estimation as to the total population size.  

This lab satisfied three objectives:

• To learn the “mark and recapture” technique for estimating the size of a population.
• To calculate the size of a population from given data.
• To make predictions about the size of a population under various conditions.

I generally do not like "simulation-type" labs such as this one, but I am always very pleased with the results and the concepts that my students learn from this lab. The students are able to carry out mathematical calculations to determine the population size, and calculate their percent error. The final analysis questions are thought provoking and require critical thinking skills. All in all, this has all the components of a great lab activity.

The Wild Bean Population

We Stop for Turtles!

Today after school, my daughter and I were driving home.  As we turned onto a very busy street, we noticed a VERY LARGE turtle topple off the curb and into the street.  The poor guy landed upside down!  I need a bumper sticker that says "I brake for turtles!"  We stopped and picked up the turtle and put him in our car.  We released him into our pond, and I hope he lives happily ever after.

Let the Student Design their Own Experiment

Can we teach our science students how to be successful conducting open-ended labs?

As teachers, we can teach the steps of the scientific method until we are blue in the face.  Many times, all we succeed in doing is having the students memorize the 6 steps to the scientific method and then repeat them on a test.  Too often science teachers conduct laboratory activities in which students follow a list of steps and record an observation at the end.  I need to be one of the first in line to say "Guilty!".  

Today's science educators are pressured to have successful end of course scores.  Sadly, a student can often perform well on these standardized tests without every doing any "real" laboratory work.  One of my goals this year is to change the focus of my class.  I am going to devote the time it takes to allow my students to write and carry out open ended lab experiments.

I have been back in school with my students for one week now.  I have covered the scientific method and gone into great detail on how to design an experiment.  We have mastered (I think!) how to define the experimental group and the control group.  My students can identify the independent and dependent variables.  They understand that only one variable can be changed at a time, and that all other variables must remain constant.  They can write a hypothesis and a conclusion.  We are just about ready to put all we have learned into practice.

I have written a PowerPoint that my students responded to extremely well.  It covers the scientific method with slides that are bright and colorful and visually attractive.  You can download this from my store, Amy Brown Science,  on TeachersPayTeachers.com.  It comes with a set of notes for the teacher and a notes outline for the student.  The student fills in the notes as the lesson is being taught.  I feel that this PowerPoint goes beyond just listing the steps to the scientific method.  Students are given practice problems in which they have to apply what they have learned.  Here is the link to my PowerPoint and notes:  Scientific Method PowerPoint with Notes for Teacher and Student.

You might also want to consider:
Scientific Method Homework
Applying the Scientific Method and Scientific Writing

Coming up this week.... I am taking my students to the lab to conduct their first open ended experiment.  It is going to involve the germination of seeds.  It will be a simple idea and will use only simple supplies.  Perhaps it may end up being more of a "guided" inquiry, but we have to start somewhere, right?  Later this week, I will post about how this goes and have some pictures as well.

Have fun teaching!

Science Illustrated: A Great Resource for the Classroom!

I NEVER want to see this look in my class!!

And I am sure that you do not either.  I am constantly on the look out for tidbits of new and/or interesting science news to use in my classroom.  My students look forward to "Hey guys, did you hear about "blah blah blah" on the news?"  Or,  "Hey guys, look at this cool video I found!"

This does not distract from the objectives of the day, and it only takes just a few minutes.  But the pay-off is huge in terms of student interest in my class.

One of my favorite sites for information is Science Illustrated online.  The news is current, fun, exciting, and most importantly....not too lengthy!!  I love that there is a wide range of areas to choose from:  Science, Nature, Technology, Space, Culture, and Medicine.

You will find a wide range of articles, glorious and interesting photographs and short video clips.

Have Fun Teaching!!

Do you love Pinterest?

Are you a Pinterest addict yet?

If you have not taken a look at this site yet, then don't delay!  Head that way right now.  Pinterest is the latest craze and people are pinning like mad.  What are they pinning?  Just everything under the sun, from recipes, to clothes, to science products (!), to favorite books and movies.  Pinterest is like a huge bulletin board.  If you have something you like, you can pin it to a board that you have created.

I hope that you will check out all of my boards.  Most of my boards are related to teaching science and you will find some great teaching materials there.  I have also found some terrific recipes on Pinterest and have pinned them to my "recipe" board.  The chocolate souffle recipe I found is to die for!

Check out my pin boards here:  Science Stuff on Pinterest!  I would love for you to become one of my Pinterest followers.

Science Skills: Using Graphic Organizers to Master Science Information

We all know that the volume of information in a science textbook is overwhelming for many of our students.  Take time at the beginning of the school year to teach some simple skills to help your students learn to organize the information into a manageable form.  We have a saying in my classroom:  "Be the master of the information.  Do not let the information master you."

With just a little direction students can learn a few techniques that will help them master the information all year long.   Science is so orderly and logical that the use of graphic organizers as a study technique makes perfect sense.  There are many different types of organizers, but the ones that work best for me are concept maps, event chains and cycle maps.

At the beginning of each year, I take the time to teach this important skill to my students.  I give them passages to read and then we practice organizing the information using either a concept map, an events chain or a cycle map.

At first I give the students a diagram to fill in, such as the one seen below:

But very quickly I have my students designing and drawing their own concept maps.  Once students get the hang of the technique, many of them find it to be a fun and enjoyable way to study!

Graphic Organizers: Tools for Mastering Science Concepts

HELP! The science vocabulary is killing me!!

Anyone who has ever taught or taken a science class knows exactly what is meant by the title of this article!

Students of all ages, enrolled in all sorts of different science classes, are faced with this age old problem.  I think there must be a conspiracy going on.  I think there is a little room somewhere, where the great scientific minds come together and challenge each other to come up with the wildest and most difficult words possible.  I actually had a student say this in class once!  As if learning the scientific concepts wasn't already hard enough, let's throw out anthocyanin, bioluminescence and cephalization!

Sometimes I feel like I am beating my students over the head with vocabulary words!  I teach my class in a very conceptual way.  I want them to UNDERSTAND concepts such as protein synthesis, photosynthesis and cellular respiration.  The understanding of the process is more important than being able to spout off a bunch of fancy words.  However, in order to explain and understand the concept, the student must be versed in basic vocabulary that can be used to explain the idea.

I start off each and every new school year with an activity called "What's in a Name?"  This activity contains 50 prefixes and and 30 suffixes that are commonly used in the vocabulary words of a life science or biology class.  I have the students practice making words with the prefixes and suffixes and I also give them a list of words that they have to decipher.

Take, for example, the words I listed above:

• Anthocyanin:  "Anthos" means flower and "cyan" means blue.  These are blue, purple and red pigments found in flowers.
• Bioluminescence:  "Bio" means life and "lumin" refers to light.  This is the production of light by living organisms in certain chemical reactions.
• Cephalization:  "Cephal" refers to the head.  This is the formation of the brain in the anterior part of the body...the head.

By providing your students with a basic set of prefixes and suffixes, and requiring that they learn these at the beginning of the year, you have given your students a tool that can be used all year long.  I require that my students memorize my list, and we quickly have a test on the terms on the list.  The students will moan and groan, but they will already know many, if not most, of the terms on the list:  micro, macro, bio, photo, cyan, poly, di, mono, etc.

After doing this exercise with my students, I see the reward of it all year long.  It is such a great feeling, when later in the year, I see a student breaking a word down into individual parts and realizing that they can give a basic definition to a word they have never seen before!

Have fun teaching!

Here's the link to: Biology Prefixes and Suffixes: Master the Science Vocabulary