History of Life on EarthBig IdeaEvidence for Earth's history can be found today.Essential Questions
How the Earth Was MadeNow we will discover Darwin's next big lesson that helped him develop his theory. In order for natural selection to produce the many species alive on Earth today, there would have to be a very long time, but people believed the Earth only existed as long as humans had existed. In Darwin's time, we were discovering that the Earth was much older that we thought before. Watch the History Channel Special "How the Earth Was Made" to find out what Darwin knew and what we know now. (The full video is available on iTunes if you missed it, or you may watch during tutoring. It's #6 on the list.)Extinction: Here Today, Gone TomorrowThe Asian elephant is endangered. Should we save it? You might think this is a no-brainer, but it's more complicated than it might seem. Read about the benefits and trade-offs of saving these amazing creatures in the article "Here Today, Gone Tomorrow." What about going one step further. Should we bring the extinct woolly mammoths back from the dead? Some scientists are hoping to clone them from the cells in frozen mammoths. What do you think? Is it a good idea?Use the question at the beginning of the article as your guiding question. Write it at the top of your page under the title. At the bottom of your page, save 4 lines for your answer, which is your summary. Then split the middle of your page into two columns and make a list of benefits and trade-offs of saving the endangered Asian elephant and of bringing back the woolly mammoth from extinction. (The article can be found in Google Classroom or see me to borrow the book or a copy of the pages.)
- Describe how life has changed over Earth's history.
- What evidence do we have to show what life was like?
When you are done reading and making notes, work with your group to create a poster supporting your point of view. Here are some things to keep in mind to make your poster most effective:
Cladograms - A Kind of Family TreeYou've seen family tree diagrams, and in genetics, we used pedigrees to show family relationships. Cladograms are similar in a way, but they are used to show evolutionary relationships. Organisms that are more closely related will be more closely connected in the cladogram. To get a brief introduction, watch this short animation, "How to Build a Cladogram."Now let's build our own. You have 5 cards with the skeletons. Four are whale ancestors and one is a modern whale. Let's examine the skeletons to find similarities and differences and build a cladogram showing how they are related. We will also add the characteristics of their common ancestors. Here's how:
- Pictures are powerful (please don't use graphic/disturbing images)
- Make short, clear statements supporting your point is large lettering.
- Use smaller lettering and longer statements to
- explain what you are willing to trade-off and why
- give details explaining your opinion
- Each person in the group must contribute from his or her own sign-in.
- Sort the skeletons into two groups based on their similarities. Call one group "A" and the other "B."
- In your notebook, do a Venn diagram comparing group A fossils to group B fossils.
- Create a cladogram.
- Connect the species in group A to each other.
- Connect the species in group B to each other.
- Connect group A to Group B.
- At the place where group A connects to group B, write the characteristics that both groups A and B share. These are characteristics of their common ancestor.
- At the place where group A species connect to each other, write the characteristics they share. These are the characteristics of their common ancestor.
- At the pace where group B species connect to each other, write the characteristics they share. These are the characteristics of their common ancestor.Congratulations! You created a cladogram!What is a Fossil?To learn how fossils formed, watch the BrainPOP video called "Fossils."What Can We Learn From Fossils?Have you ever seen movies with dinosaurs running around? What about the documentary specials that are supposedly non-fiction? Where does the video of dinosaurs come from? There were no cameras when the dinosaurs lived, no Discovery Channel, and no Instagram, so how do we know what they looked like? Can we tell how fast T-rex could run? What color was a triceratops? Can we really know the answers to these questions? Examine some fossils on your own to see what we can (and can't) learn from them. Work with your group to create a Google Slides presentation about your fossil organisms. For each fossil, create two slides. Put the following information on the slides. Write your answers, please. Don't copy the questions. Put short bullet points on your slides. When you present, you will speak in complete sentences, though.Slide 1 - Observations
Slide 2 - Cladogram
- Picture of your fossil. (Find your fossil on the Fossil Photos page.)
- How large is the fossil? (not the rock, the fossil. Measure length, width, diameter, height. Whatever makes the most sense.)
- Describe the fossil's shape. (In detail! Don't just say "oval" or "circle.")
Slide 3 - Inferences
- Choose 2 modern organisms. One very similar to your fossil organism, and one different.
- Create a cladogram of your 3 organisms.
- At each branch of the cladogram, put at least one characteristic of that common ancestor.
Relative DatingNo, it's not when you go out with your cousin. At least that's not what we're talking about in science class. Relative dating is figuring out how old rocks and fossils are compared to, or relative to, each other. To learn how rock layers form, watch the beginning of the Grand Canyon episode of "How the Earth Was Made." (7:30-10:35) Which layers formed first? Think you understand it? Find out by playing the stratigraphy game "Relative Rock Layers" from Science Learning!How do we know what the layers of rock look like below the Earth's surface? In some places, like canyons or the shoreline, we can see the layers where erosion has cut into them (See the picture on the right!), but what about the layers below that? Or the places where erosion hasn't exposed them? We can learn about those by drilling samples and drawing inferences. To see how we drill core samples, watch this demonstration video about the SonicSamp Drill. To understand how we use the data from our samples, try it! In class, we have some faux "core samples." Record the data from your core samples and try to re-create on your worksheet what the layers of rock look like below the surface! When you're done, the rock layers you identify should go all the way across your page, something like the diagram here.Rules for Matching layers:Absolute Dating
- In what kind of habitat did your organism probably live? (Find a picture on the web and paste it on this slide.)
- How did your organism probably move? (crawl, walk, slither, swim?) (Why do you think that?)
- What were the soft parts of your organism probably look like? (Why do you think that?)
For example: Humans have soft parts like muscle and skin outside of a skeleton and internal organs protected by bones, while crabs have long muscles attached to the inside of an exoskeleton that also protects its internal organs, and snails have a soft body that can partially come out of a shell or be pulled inside for protection.
- What is it very difficult to know about your organism just by looking at the fossil? (Why?)
Coming soon ...Geologic TimeBackgroundIf you had to make a timeline in Social Studies, and if you had to put Obama's first election to president on that timeline, where would you put it? 2008 of course. But why? And I don't mean that we don't know when he was elected. I mean why is that year called 2008? Why isn't it that year called 228 or 752? What is year 0? It certainly wasn't the beginning of the Earth. And it wasn't when humans first began keeping track of time. We had been doing that for thousands of years before year "0."So what is the "0" year? Do you remember what "B.C." stands for? "Before Christ." And what about "A.D."? Anno Domini, which means the "year of our lord," or basically, after Christ. so 2008 A.D. means that it happened 2008 years after Christ. Year "0" is when Christ lived. In geologic time, our "0" year is the present. We measure time backwards from now. In geologic time, you are always living in year "0."But how can that be? you might ask. How can this year be 0, and next year is 0 too, and last year? Actually, it's because we don't use years to measure. In geologic time, we measure in millions of years. The Earth formed over 4,500 million years ago. Earth's history is so incredibly long that years just don't make sense. It would be like calculating your age in seconds. So 2008, 2015, 2020? They're all in the same million years, so they don't really change where the "Present" is on our geologic time line.There is one way that our modern calendar and the geologic time scale are the same. Starting with Christ's life made sense when Christians were making the calendar. The most important event they could think of was Christ's life, so they used it to mark the beginning of a new time period. In geologic time, we also begin new time periods when there is a significant event, but we use significant events from the fossil record instead of human history. These events can include mass extinctions and the sudden appearance of new types of organisms. For example, the extinction of the dinosaurs was a significant event that occurred 65 million years ago (before the present). That was the end of a time span. The first living things appeared on Earth around 3,500 million years ago. That was the beginning of a time span.We're going to make a timeline of all of Earth's history. This timeline will show the major time spans in geologic history, the significant events that begin and end them, and the distinctive fossils from each time period. You will be taking an open-timeline quiz on this information, so make sure your timeline is accurate!Personal TimelineTo get started, we're going to make a short timeline of your life, geologic time style. Like geologic time, we will measure backwards from the present; the present will be "0," and we will divide it into time spans using significant events. Since none of you were born a million years ago, though, we will use y.a. (years ago) to measure instead of m.y.a. (millions of years ago).These are the events that will go on your timeline:
- The rock types must match.
- There must be at least one matching fossil type.
(Ex: Trilobits and ammonites matches trilobites only, but Trilobites only doesn't match ammonites only.)
- If the layer is correctly matched, all the layers above and below will match too.
- Hint! If you do this correctly, one layer, and one layer only will match all the way across the page.
- I began kindergarten.
- I came to science class.
- I learned to read.
- I got dressed this morning.
- I finished elementary school.
- I ate lunch.
- I was born.
- I learned to walk.
ScaleWe're going to make a timeline of the entire history of the Earth! How old is the Earth? That's right 4.5 billion years ... Hey, wait a minute, our rulers don't have billions of years or millions of years or even years. How will we know how long to make each time span? Looks like we're going to have to use a scale. Since our rulers have centimeters, we have to figure out how many years equals a centimeter. That is our scale!Before we calculate the scale of our timeline, let's just practice using a scale. On our scale worksheet, we will be making shapes larger and smaller based on a scale factor. If the scale says 1:2, that means that for every square on the original, you will put 2 squares on the new shape. That means the new shape will be twice as large as the original shape. Try it!Geologic Time Span DragsterNow that you understand how geologic time works, it's time to look at actual geologic time periods. In human history, we have time periods like the Industrial Revolution and the Renaissance. What about geologic time? We have geologic time periods too, but they are based on what kinds of organisms lived during those times, and geologic time spans last a LOT longer than periods in human history. Geologic time periods begin and end with significant geologic events. Why? Because major changes in the environments organisms lived in led to mass extinctions and the development of new species.In this activity, you will use clues about the significant events and notable fossils from each major geologic time span. Do you think you can put the time spans in the correct order (without their names and without looking it up)? Try the Geologic Time Spans Dragster to find out! Aim for 100% on your first try. Don't just submit it over and over and let the computer tell you where they go. Use the clues and logic. For example, will any fossils exist before the formation of Earth? Can dinosaurs exist before the first land plants? Can corals exist before the first multi-cellular organisms? The clues are there, use your detective skills and figure them out!When you are done:
- Write the word "Present" at the top.
- Under that, put the most recent event; then write the other events in order backwards in time.
(So the event that happened the longest time ago should be at the bottom of your list.)
- Next to each event, write how many years ago it happened.
If it has been a very short time ago, like today, it hasn't been a year, so you would put "0 y.a." If you are 12 years old, then "I was born" happened 12 y.a.
- Pick which event on your timeline was the most significant change. Draw a line across your page that divides your timeline into two time periods at this point.
This can not be your birth or events that happened today. You must choose something in the middle. For me, it was "I learned to read," because I love reading and I love learning. I would have been a very different person if I didn't learn that.
- Name your time periods.
Geologic time spans have names like the Cambrian, Precambrian, Carboniferous, and Devonian. Create names for your time spans that relate to what happened then. I named the time span before I learned to read, the "Prereadian" and the time period after I learned to read the "Readian." Make up your own names.
Doing the Math
- Take a screen shot of your answers. These will be your electronic notes for your Geologic Timeline.
(If it turns out your answers are wrong, you can go back and take another screen-shot when they are all correct.)
- Click on the check box at the bottom right to submit your answers.
Put the number of your period, your last name, then your first name.
For example, if I were in period 4, I would put: 4 Armstrong, Valerie (Please capitalize like scholars.)
(You may put a personal email if you want scores emailed to you, but it is not required. The school email will not work.)
- Use your Dragster answers to fill in the notes on your Geologic Timeline worksheet.
There are 6 major divisions of geologic time on our timeline. They go in the same order on your Dragster and your notes. In the section that says "Key Events," fill in the events that happened and write whether they happened at the beginning or end of the time period. Also look at the notable fossils and make notes on what kind of organisms lived during each time period. Pay special attention to which organisms first evolved.
We're making a timeline of Earth's history. Earth's history is 4.5 billion (4,500 million) years long. Do you have the right ruler for that? Does your ruler have millions of years on it? Mine doesn't it only has centimeters. Yours too? Well then, I guess we'll have to use a scale factor to convert millions of years to centimeters. The timeline will be 90cm long and will represent 4,500 million years (that equals 4.5 billion) Can you set up a proportion to figure out how many centimeters equals 1 million years? Your answer is the scale factor. We will use the scale factor to figure out how many centimeters long each time span should be on our timeline. (Hint: Check your answer by using the Early Precambrian. If you multiply 700 my times your scale factor, the answer should be 14cm. If not, you did something wrong.)
Remember the scale worksheet with the different shapes we had to make bigger and smaller? If the scale was 1:2, the scale factor was 2, and we had to multiply every line by 2 to make the shape twice as large. If the scale was 1:3, the scale factor was 3, and we had to mulitply by 3, etc. Your scale factor for the timeline will work the same way. For each time period, you will multiply the length of time (in millions of years) by the scale factor, and it will tell you how many centimeters long that time span should be on your timeline. Round to the nearest tenths place; i.e. 1.475 would round to 1.5.Making the TimelineWe keep saying we're going to make a timeline. Well the time is finally here (yay!!). You will need a long receipt paper at least 90 cm long. I recommend 1 meter. On that paper:
Owl PelletsIn order to understand evolution, we need to use a lot of the vocabulary and concepts we learned in our previous units. You need to know about basic anatomy, especially bones. You also need to know how ecosystems work, and you need to understand genetics. We will put all this together in our evolution unit. We'll start by reviewing anatomy and ecosystems while we dissect owl pellets!What's an owl pellet? It's the parts of an owl's meal that it can't digest. The owl swallows its prey whole; then the owl's gizzard separates the part of the prey that it can digest from the fur, bones, and any other parts that it can't digest. The owl then regurgitates the indigestible parts.Why dissect something so gross? It will show us how we can study an organism's habitat and its role in the habitat without even seeing the organism itself. It will also be a good review of bones and anatomy, which will help us get ready for our evolution unit! Three in one!Your job is to dissect an owl pellet and determine what the owl ate in that meal. Did it eat a rodent? Did it eat two rodents? Did it eat a bird or insects? After you dissect it, you will assemble the skeleton or skeletons on a sheet of construction paper. This is your data to support your answer.Before we began the actual dissection, we did a virtual dissection. This was to help us learn the shapes and names of the bones as well as how they fit together. Then we did the Owl Pellet Bine Identification QuizStar to prove that we really learned it. You must get 100% on the QuizStar to begin the dissection. It's not a quiz, though, so be sure to ask for help if you get stuck! The purpose is to learn. Here are some tips:
- Put your name on the back of your paper.
- Draw the line part of your timeline down the length of your paper. It should be 90 cm long.
- Measure each time period and mark the dates for the beginning and end. (Ex: The Early Pre-Cambrian begins at the far left on your line. It starts 4,500 mya and ends 3,800 mya. The length of this time span should be 14 cm on the timeline.)
- In the middle of each time span, write the name of the time period.
- On your worksheet, there is a list of significant events. Put each event on your timeline where it belongs. Remember, geologic timespans begin and end with significant events, so none of these events should be in the middle of a time span.
- In each time span, put at least 1 drawing or picture showing the type of organisms typical of that time period. (See your notes from the Dragster.)
- Color your timeline and make it beautiful!
- Place all the LARGE bones on the skeleton.
- DON'T put all the vertebrae on the skeleton.
In fact, only put one or two vertebrae in each part (cervical, thoracic, lumbar, and caudal). If you put them all together,there will be 3 problems: 1-The bones will animate and disappear, so you won't be able to look back at them while you do your QuizStar. 2-It will take a long time. Remember, your grade is based on the QuizStar, not the virtual dissection, and 3-You won't be able to see the shape of the individual vertebrae (They are different in each part of the spine. On your QuizStar, you will need to know the shape of the different types of vertebrae).
- It is hard to tell the difference between the pelvic bone and the tibia-fibula. Although they both have holes in one end, the shape is different. The end of the tibia-fibula looks a little like a bow for a bow and arrow. The tibia is thick and bows outward, the fibula is thin and straight like the string of the bow. The end of the pelvic bone, on the other hand, has a triangle shape and no skinny, straight part.
- The pelvic bone connects the leg to the spine, it is NOT part of the leg. The femur is the upper part of the hind limb.
- The rodent's forelimbs are the legs that are closest to the head. They come beFORE the other legs. Its hind limbs are the legs that are beHIND the forelimbs.