Evolution and the Geologic Time Scale

The concept of geologic time and the appearance and evolution of life on Earth is VERY important to my class. One of my most favorite sayings, "Nothing in Biology makes sense except in the light of evolution" (Theodosius Dobzhansky, American Biology Teacher, 1973.) is a mantra in my classes. We can't teach cellular respiration without the concept of endosymbiosis, and we can't teach endosymbiosis until our students know the differences between prokaryotic and eukaryotic cells, etc, etc, etc. The history of life on Earth is (or should be!) woven into every single lesson we teach in a Biology class.

Then "What's the problem?" you might be asking yourself. My problem is time. Not geologic time;  just time to teach. It is a struggle to cover everything in a year that needs to be covered! My solution was to find a way to quickly cover the concepts of geologic time and the evolution of life on Earth, without taking weeks to do so.

Here are my goals.  I want my students to:

• Know what is meant by the term "geologic time scale."
• Be able to visualize the enormity of geologic time.
• Know when life first appeared on Earth.
• Know the order in which various life forms appeared.
• Know the importance of fossils, especially traditional fossils, to the study of evolution.
• Understand how scientists are able to date fossils that are found in various rock strata.
• Understand the relationship between mass extinctions and adaptive radiations.
• Have a clear and concise understanding of what happens in each era of Earth's history.

I am extremely pleased with the Geologic Time Scale activity I put together to accomplish these goals. This resource can be used in conjunction with your other lessons and materials you use on this topic, OR, (and here is the best part!) it can be used as a stand-alone activity that quickly covers the above topics in just a couple of class periods.  The printable version is perfect for traditional classroom settings, but there is also a digital Google Apps version for distance learning and 1:1 schools.

If you need to teach this fast, this is the activity for you!

What concepts are covered in this resource?

• Definition of the geologic time scale.
• How the geologic time scale was developed by scientists.
• Relative dating and Radioactive dating.
• Earth’s history is divided into 4 Eras which are subdivided into smaller periods.
• How to read the information on the geologic time scale reference table.
• Comparing lengths of geologic time.
• The order of events in the evolution of life on Earth.
• Transitional fossils.
• Estimating the age of organisms based on relative dating.
• Rock strata.

What will the students be doing?

• Students complete a 6-page handout on the geologic time scale and complete a 2-page timeline of the history of life on Earth.
• Students make a circle graph of the time spent in each era.
• Students use the included Geologic Time Scale Reference Table to answer a series of 30 problem solving questions.
• Students make a scale diagram showing the length of each era.
• Students look at pictures to evaluate characteristics of certain organisms.
• Students complete a relative dating cut and paste activity.
• Students using relative dating to estimate the age of certain organisms.
• Students complete a 2-page cut and paste timeline activity showing the evolution of life on Earth.
• Students are guided through an exercise that allows them to compare all of Earth’s history to one calendar year.

As much as I love teaching these topics, there is a limit to what we can expect our students to absorb. We can't ask them to learn every event in every era, period, and epoch in geologic time. I have certain key events that I want my students to know, so I put together a one-page table outlining the most important events in Earth's history.
  

The beauty of this resource is that with this one-page reference table the activity can be used as a stand-alone lesson. The students don't need prior knowledge or prior teaching. This lesson can be completed in two 1-hour class periods right before you begin your units on evolution. I would suggest having a biology textbook handy if students are seeing this information for the first time. There may be a few vocabulary words that they would need to look up.

If you are in a big time crunch, let the students work in groups for one class period, and complete complete unfinished portions for homework.

You can find this activity in my TpT store by clicking this link, and here is what you can expect to find included:

• 6-Page printable and editable student worksheet set
• 1-Page Geologic Time Scale Reference Table
• 2-Page Timeline Worksheet
• 8-Page Teacher Guide and Answer Keys
• All images needed for the "cut and paste" portions of the activity.
• Paperless digital google apps version for use in Google Drive, Google Classroom, Microsoft OneDrive, or similar.

I hope this article has given you something to think about, and some new ideas on how to teach geologic time to your biology or life science students. Have fun teaching!

Charles Darwin: The Tale of Evolution

Over 130 years have passed since the death of Charles Darwin.  Despite the passage of time since Darwin first presented his ideas on natural selection, there continues to be controversy surrounding his theory of evolution.  In 1973, Theodosius Dobzhansky published an essay in American Biology Teacher in which he stated, “Nothing in biology makes sense except in the light of evolution.”  Truer words were never spoken.  When teaching a biology class, we shouldn’t limit our students to a single unit on the theory of evolution.  Rather, the theme of evolution should be woven throughout every unit we teach.

I designed this teaching resource to teach my biology students about the man, Charles Darwin.  Darwin was a religious and thoughtful man, as well as a superb scientist.  However, I have found that I still have students in my class who view him in a less than complimentary light.  My main goal in writing this journaling activity was to provide my students with the facts and information they need to form their own opinions and conclusions based on the evidence presented.  After all, that is the goal of science, right?

I had two goals in mind when writing “Darwin’s Diary.”  First, I wanted to include enough biographical information about Darwin to teach my science students about his life.  Second, I wanted to produce a class project that would require my students to be thoughtful and introspective, while at the same time, ensure that they master the concepts of evolution.

What will the students be doing?

This teaching resource is written as if it were a diary kept by Charles Darwin throughout his life.  The entries in the diary are designed to teach about the life of Darwin, and the events that led him to develop his theory of evolution.  The 26 diary entries include facts and information about Darwin as well as actual quotes from Darwin.  Students are asked to respond in some way to each diary entry.  In some diary entries students will be asked to offer opinions, but in others, they must provide correct answers to questions.  In order to complete this project, students need to receive instruction in the concepts covered in an “Introduction to Evolution” chapter of a typical high school biology textbook.

Click on any image to view this resource in my TpT store.

I had such a great time doing the research for this evolution journaling activity! Darwin's life was full of the same drama, struggles, accomplishments, and tragedies that we all face today.  Darwin was witty, introspective, and very adventuresome!  I was able to find and use his own writings to use in the diary entries, and his descriptions of his daily life are simply amazing.  In one dairy entry Darwin describes collecting beetles.  Both of his hands were full holding beetles, so in order to catch a new beetle, he popped one into this mouth to free up a hand to catch another!  He describes his struggles trying to please his father, his tiny quarters aboard the Beagle, riding on the backs of Galapagos turtles, marriage, and his concern about the uproar that would be caused by publishing his theory.  As you can see, I am completely captivated by the details of his life, and your students will be as well!

What is needed to complete this assignment?

In order to complete these assignments, students will need to use the following resources:

•  Biology textbook

•  Notes taken during class

•  Online Resources

This diary activity is perfectly aligned with my teaching PowerPoint, “Darwin’s Theory of Evolution.” It includes a 96-slide PowerPoint with notes for teacher and students. Click the image to the right to view this product on TeachersPayTeachers.

How can you use this in your classroom?

•    I suggest copying all pages and passing them out to your students on the first day of your evolution unit.  The activity is designed to be used over multiple days as you teach your unit on evolution.  

•    Use only the pages you want.  There are enough student pages included so that you have the flexibility to choose the pages best suited for your needs. 

•    Each day during your unit, have students complete a number of the dairy entries.  These pages make great classroom activities as well as quality homework assignments.  You will find that the content of the diary entries will generate much classroom discussion.

•    The questions used in this assignment are of two types.  Some questions require the students to express their opinion, but most questions require a research-based correct answer.  I accept any and all answers to opinion-based questions as long as the student has given an honest effort to express his/her opinion.  If this assignment is to be graded make sure that students know that they are expected to provide correct answers for the majority of the questions.

      

    At the end of "On the Origin of Species", Darwin writes, “There is grandeur in this view of life … from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” This teaching resource is a journey through time that allows our science students to learn about the events throughout Darwin's life that led him to write and publish "On the Origin of Species by Means of Natural Selection."

  

Evolution and Classification Warm Ups and Interactive Notebook Pages

Do you love teaching about evolution or dread it?

I am the biggest biology nerd ever, so I love ALL of biology.  But I really, really, really love teaching about evolution, followed up with classification.  My first year biology students have very poor (and uninformed!!) ideas and knowledge about evolution.  For many of them, it is the first time they have been taught about it.  Others come with a lot of misinformation.

This makes for such a fun teaching situation!  Just for kicks, ask your students about their opinions on the topic of evolution BEFORE you teach them the unit. I am always amazed at their misconceptions and poor knowledge base.  When you have finished teaching your unit, ask the students again about their opinions.  I love that over the course of a couple of weeks the opinions of many will be changed, and the knowledge level of all has been increased.

And the best part?  There is never a dull moment in class.  I love the discussion and the questions and the arguing!  I love to see the wheels turning in their brains.

Since this material tends to be new for most of my students, I developed a set of 61 warm ups / bell ringers / interactive notebook pages to use during the unit.

There are so many ways to use these pages.  I have my students keep a "Biology Warm Up Notebook."  It is a perfect way to review and reinforce material from the previous day, and it is a fantastic classroom management tool. 

My students come in, grab the warm up and get right to work. By the time I have finished taking roll, answering questions, dealing with the "stuff" that we teachers always have to deal with, my students are settled down and are already hard at work. There are too many pages to be completed in class, so I often use them as homework assignments, and review guides for the unit test.

Keeping a "warm up" notebook provides a perfect way to
review for the semester exam or end of course testing.

Below is a table of contents.  The 61 pages include all of these titles.

Here is a look at format.....

As always, I hope you are having a terrific year with your students.

Links to all Warm Ups / Bellringers/ Interactive Notebook Topics:

Introduction to Science

Cell Structure and Function

Ecology

Genetics

DNA, RNA, and Protein Synthesis

Evolution and Classification

Population Genetics: The Hardy Weinberg Equation

This fun lab simulation should guarantee that your students understand the Hardy Weinberg Principle!  

I talk to a lot of biology teachers. Everyday. Some are in my school, some are at other schools in my district, others I know "virtually" from various message boards that I read and post to.  Through these communications, I have come to realize that many biology teachers do not include the Hardy-Weinberg Principle in their lesson planning.

I know that all biology teachers have their own "order of events" but for me a unit on genetics, followed by my unit on evolution is perfect.  In fact, I would be hard pressed to do it any other way.  The Hardy-Weinberg Principle is the link between genetics and evolution.  It is the proof that we offer to our students that populations are constantly changing and evolving.  It allows us to mathematically show that the frequency of a particular allele in a population can change over time.

Simply put:  Evolution is any change in the frequency of alleles in a population.  Evolution is the result of changes in the gene pool.  Two men, G. H. Hardy and W. Weinberg, proposed a mathematical model for detecting changes in the gene pool.

The Hardy-Weinberg Principle states:  “In the absence of mutation, migration, and natural selection, and in a population that is sufficiently large, the frequencies of alleles will remain the same.”  

The Hardy-Weinberg Principle is represented in the equation:

No population is free of these agents of change.  The Hardy-Weinberg equation is used to detect changes in the population from one generation to the next.  Since no population in nature is free of mutations, migrations, and natural selection, and since mating is rarely completely random in nature, of what value is the Hardy Weinberg Principle?  It allows us to detect changes in the gene pool, and therefore, determine that a population is in a state of change....Evolution!

My experience with my own students is that some of them have a little trouble grasping this concept. After introducing the topic and working through quite a few practice problems, I do a simulation lab.

Purpose of the Lab:  
1.  To simulate how changes in the gene pool might occur by using the class as a breeding population of individuals. 
2.  To observe how the Hardy-Weinberg equation is used to detect changes in allele frequencies in a population.

Materials:   PTC test papers,  Calculator,  Allele cards,  Coins, Pencil and paper

Safety Precautions:   None

The student handouts for this lab are numerous.....12 pages!  I usually run off a class set and have students record all of their information on notebook paper. I use the class set throughout the day, and then I file them away for use the next year.

I have also included an 11-page teacher guide.  The teacher guide has tips and tricks for making the lab successful as well as answers to questions and solutions to problems.  Sample data is included to give you an idea of what to expect in the simulation.

Students begin the lab by determining the frequency of an allele in the class population.  I like to use PTC paper to determine if students are tasters or nontasters. But if PTC paper is not available, you can choose another trait such as the presence or absence of dimples, or the ability to roll the tongue.  From the number of recessive individuals in your class, the value of q can be determined.  From that point, the students will determine what percentage of the class is homozygous dominant and heterozygous for the given trait.

Next, students will run three simulations:  (1) Testing the Hardy-Weinberg Principle, (2) Testing the Hardy-Weinberg for Selection Pressure, and (3) The Heterozygote Advantage.

Students will begin the simulation as heterozygous individuals and will use allele cards to generate offspring. Students proceed through several generations of "mating" and the data is used to test the different conditions of the Hardy-Weinberg Principle.

During each simulation, students will determine the frequency of the dominant and recessive allele and note how the frequency of p and q change in various scenarios. The lab concludes with follow up questions and 8 additional practice problems involving the Hardy-Weinberg equation.  

The end result?  My students have mastered the concept and are able to work problems involving the Hardy-Weinberg equation.

Good luck, and have fun teaching!

Lab:   Population Genetics,  The Hardy-Weinberg Principle, and Evolution