Understanding the past is a key to understanding the present and

Document Sample
Understanding the past is a key to understanding the present and Powered By Docstoc
					                             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)



LEARNING STYLES: Visual, auditory, tactile/kinesthetic

    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

   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

    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

MATERIALS: Materials listed are for one class of approximately 30
      -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
      (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
      All)), etc.

      -Classification Worksheet (attached)
      -Animal Character States Worksheet (attached)
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.

       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
    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.

       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).

      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.

       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
Picture 1. An artist’s depiction of a sea ammonite, a shelled creature that
lived over 150 million years ago.


Picture 2. A fossilized sea ammonite shell.

      Shepherd, R. “Fossils: Bringing the Prehistoric World to Life.” 2008.
27 June 2008 <www.discoveringfossils.co.uk>.

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
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.

Shared By: