A-Bug and Beyond Prepared for SPICE by Kelly Sims and Dale Witt Illustrations by Jane Dominguez Lesson One: Fly Back to the Past with Fossils KEY QUESTION(S): What are fossils? How are fossils important to us? Who studies fossils? How have fossils helped us classify organisms? SCIENCE SUBJECT: Earth Science (Geology, Paleontology) GRADE LEVEL: 6th OVERALL TIME ESTIMATE: 60 min. LEARNING STYLES: Visual, auditory, tactile/kinesthetic VOCABULARY: Fossils - the remnants or imprints of plants and animals that have been preserved by natural processes of the Earth Paleontologist - scientists that study plant and animal fossils to make inferences about the past Inference – an assumption based on an observation Classification – a systematic arrangement in groups or categories according to criteria LESSON SUMMARY: This lesson consists of three exercises that are independent of one another and can be combined in any way the user prefers. The goal of this lesson is to teach students about fossils and their importance using a variety of techniques that merges a student’s creative ability with scientific thought. The three exercises are 1. The pre-lab (15 min.): Making inferences 2. The lab (30 min.): Excavating fossils 3. The post-lab (15 min.): Classification STUDENT LEARNING OBJECTIVES: The student will be able to 1. Explain the importance of fossils 2. Define paleontology 3. Make inferences based on fossil fragments 4. Classify organisms according to shared derived traits or characteristics MATERIALS: Materials listed are for one class of approximately 30 students. ESSENTIAL: -5 lb. bag of Plaster of Paris -15 5 oz. Dixie disposable paper cups -Large bowl and stirrer -Excavating tools such as paintbrushes, nails, Popsicle sticks, sponges, toothpicks, magnifying glasses, etc. (approximately 15 of each) -Newspaper and/or paper towels -Additional material required for this lab depends upon the user’s choice of “fossils”: (1) Insects in resin -Insects collected from nature -Epoxy resin from your local Hardware Store -Plastic candy molds purchased from any Arts and Craft store or (2) Your choice of alternative fossils. Some examples include fossil molds (https://educationalvista.com/fossil_science_kit.html), plastic insects (purchasable from your local Dollar Store), shark’s teeth (http://www.prehistoricstore.com/category.php?class=Sharks&type=( All)), etc. SUPPLEMENTAL: -Classification Worksheet (attached) -Animal Character States Worksheet (attached) ADVANCE PREPARATION: 1. If you choose to make insects in resin, you will need to prepare the samples in advance. The resin fossils are easy to make and will simulate insects trapped in amber. I highly recommend using the real insect fossils because they offer an element of surprise greater than the other fossils listed. To do so, collect insects using any of the techniques mentioned at http://insectclass.ifas.ufl.edu about a week before the lab. Store the insects in 70% alcohol (either ethanol or isopropanol) until you are ready to make the resin fossils. To make the resin fossils, simply place the dead insect in a candy mold and fill with epoxy resin. Allow the samples to dry and cut the mold out with a pair of sharp scissors. 2. You will also need to prepare the core samples at least 24 hours before the lab. To do so, choose your fossils from the list above (either insects (1) or alternative fossils (2)). Fill a 5 oz. cup approximately ½ full with plaster of Paris, drop the fossil into the plaster, and fill the cup to the top with the remaining plaster. Let the samples sit overnight and tear off the cup after the plaster has completely hardened. PROCEDURE AND DISCUSSION QUESTIONS 1. PRE-LAB WITH BACKGROUND INFORMATION (15 min): The pre-lab should be a teacher-facilitated discussion that introduces the students to fossils and the scientists who study them. Begin the discussion by showing the drawing below and ask the students whether or not this organism ever existed (Picture 1). After all the students are in agreement, ask them how we know these creatures once inhabited the Earth. Show the second picture (Picture 2) and explain how fossils have taught us a lot about our geological past. Continue the discussion with these important questions: 1. What are fossils? Fossils are the remnants or imprints of plants and animals that have been preserved by natural processes of the Earth. 2. How are fossils made? Fossils are made in a variety of ways, including permineralization, unaltered preservation, carbonization, authigenic preservation, and recrystallization. A good example to explain the process of fossilization is with a seashell, in which death of the organism, followed by deposition, permineralization, erosion and exposure creates the perfect fossil (www.discoveringfossils.co.uk). 3. Where are fossils found? According to the law of superposition, strata that are younger will be deposited on top of strata that are older. Therefore, older fossils are buried further in the strata than younger fossils are. 4. How are fossils important to us? (1) Fossils tell us a great deal about our geologic past. They can be used to explain prehistoric life, climatic conditions, and environmental change. Fossils can also be used to explain the present time by a concept called uniformitarianism, which is the assumption that natural processes that occurred in the past are the same that are occurring in the present. (2) The organic remains of prehistoric plants and animals form fossil fuels such as coal, oil and gas. Fossil fuels are a nonrenewable resource. 5. What is the difference between a cast and a mold? Casts are copies of fossilized plants or animals and molds are hollow impressions of the fossil. 6. Who studies fossils and what type of equipment do they use? Paleontologists are scientists that study plant and animal fossils to make inferences about the past (“Paleo-” = ancient; “-onto-” = existence; “-ology” = the study of). Inferences are assumptions based on observations. Paleontologists use a variety of tools to excavate fossils from the Earth. Large tools such as shovels, hammers, and picks are used to remove overburden (rock that covers the fossils) at the dig site. Microtools, similar to those found at the dentist’s office, are then used to scrape away debris from the fossil. Scientists also use computers to analyze and/or reconstruct their samples and compare what they have learned to information already known. MAKING INFERENCES (Exercise 1) The first exercise is a great hands-on activity to end the open discussion and help students to understand the concept of inference. Using the Classification worksheet, assign each student three to four different character states and tell them that these are different fossil fragments that were found for a particular organism. Have the students draw what they envision this creature to look like using all of the character states assigned to them. After the class shares their drawings, explain that each student made inferences to logically deduce what their organism would look like and that many scientists, not just paleontologists, do this very same thing. See if any of the students can guess another career where making inferences is extremely important (e.g., detectives). 2. THE LAB: EXCAVATING FOSSILS (Exercise 2) The purpose of this exercise is to give students hands-on experience with one of many careers involved in Earth Space Science. In this lab, students will unearth fossils hidden within core samples sent from your paleontologist friend. Give each student their own core sample and an assortment of tools. The tools can be anything you may have in the classroom including paintbrushes, toothpicks, nails, mallets, chisels, magnifying glasses, hammers, etc. Each lab station should have an abundant supply of newspaper and paper towel. Tell the students that a paleontologist has called upon them for help in excavating fossils; therefore it is extremely important to be careful and to not get any scratches on the specimens. Using the larger tools first (e.g., nails and mallet), have the students slowly chip away at the core sample. Once the students have reached the fossil, use the smaller tools to pick away any debris. Allow the students to compare specimens with one another. 3. THE POST-LAB: CLASSIFICATION (Exercise 3) For the final exercise of the lesson, students will work together to classify their fossils using shared physical characteristics or commonalities. Place the students in groups and tell them you want them to split the fossils into groups based on distinct characteristics that separate the samples. Have a representative from the class describe how and why they decided to group the fossils that way. See how many other ways the students can classify the organisms. Compare your class results to the actual classification using the Tree of Life website (http://tolweb.org/tree/phylogeny.html). Picture 1. An artist’s depiction of a sea ammonite, a shelled creature that lived over 150 million years ago. www.discoveringfossils.co.uk Picture 2. A fossilized sea ammonite shell. www.discoveringfossils.co.uk RESOURCES/REFERENCES: Shepherd, R. “Fossils: Bringing the Prehistoric World to Life.” 2008. 27 June 2008 <www.discoveringfossils.co.uk>. FLORIDA’S SUNSHINE STATE STANDARDS: SC.6.N.1.5 Recognize that science involves creativity, not just in designing experiments, but also in creating explanations that fit evidence. SC.6.N.2.2 Explain that scientific knowledge is durable because it is open to change as new evidence or interpretations are encountered. SC.6.N.2.3 Recognize that scientists who make contributions to scientific knowledge come from all kinds of backgrounds and possess varied talents, interests, and goals. SC.6.E.6.1 Describe and give examples of ways in which Earth’s surface is built up and torn down by physical and chemical weathering, erosion, and deposition. SC.6.L.14.1 Describe and identify patterns in the hierarchical organization of organisms from atoms to molecules and cells to tissues to organs to organ systems to organisms. SC.6.L.15.1 Analyze and describe how and why organisms are classified according to shared characteristics with emphasis on the Linnaean system combined with the concept of Domains.