We're Going on a Fossil Hunt!

Oct 17, 03:42 AM

Current Headlines: By Powell, Deborah A Aram, Richard B; Aram, Roberta J; Chase, Terry L

Abstract. Scientists understand that scientific ideas are subject to change and improvement. Fourth- through eighth-graders develop this understanding about the nature of science as they gather and examine fossil evidence from the Paleozoic era, record their findings, and read and write about science for authentic purposes as scientists do. Students recognize the tentative nature of science and experience differences in interpretation of evidence. Students also learn that scientists use writing and sketching as tools of inquiry. Keywords: earth science, fossils, nature of science, paleontology, prehistoric environments

In a recent workshop for third- to eighth-grade teachers, one of the authors of this article asked how many teachers taught students about fossils. Most agreed that fossils should be taught because they are in the curriculum and children are very interested in them.

"We usually read about fossils in our textbook," reported a fifth- grade teacher. "I wish we could do more, but we don't have any fossils."

"Shouldn't we be teaching more important and timely topics, such as the environment, worldwide changes of climate, or extinction?" asked another teacher.

"Or we should be teaching organizing concepts such as systems, order, and organization," added another teacher.

". . . or the origins of life," chimed in a yet another teacher.

In many ways, fossils provide some of the best data for all of these topics. Fossils record more than six million years of history, whereas modern mammals represent a very tiny fraction of that time. Regarding climate changes, fossils tell us that the center of many continents used to be covered by ancient seas. How do we study origins scientifically- can we experiment, or do we observe it happening? Again, fossils are the best evidence.

Children become curious when they discover what looks like a small bit of animal protruding from a rock or the impression of a shell left behind millions of years ago. Unfortunately, few instructors know enough about fossils to guide their inquiries. How many of us know a brachiopod fossil from a bryozoan fossil? Still fewer instructors have a suitable collection of fossils to teach from. In this simulation, third- through sixth-grade students learn how to collect and interpret data as they compare the characteristics of newly discovered "fossils" from a local rock outcrop with those sketched in the field notebook of a fellow scientist.

Although real fossils make a great supplement to this activity, teachers without a fossil collection can guide students to discover that fossils provide evidence of the nature of the environment long ago. Students develop their own scientist's notebook, which provides opportunities for them to write about science and learn that science is not about memorizing answers but collecting data and making new interpretations from existing data.

Background

Paleontology is the science of using fossils to study life in past geologic time periods. Fossils are the recognizable remains of organisms that once lived and include bones, shells, leaves, and indirect "trace fossil" evidence such as tooth marks, tracks, burrows, nests, eggs, and impressions. Fossils are often discovered where natural erosion or human excavations have exposed fossil- bearing rocks. Field paleontologists collect fossils and maintain a careful and thorough field notebook that describes the precise geographic location and rock layers in which the fossils were found.

Most fossils were formed in sedimentary rock, which is formed in layers (or strata) as sediments are deposited on top of older sediments. The weight of the pile of sediment packs and cements them to create harder rock. Sediments include pieces of rocks, sand, clay, and silt, as well as dead animals, plants and their shells, bark, and skeletons. The heaviest or largest particles settle first, so the oldest layers are on the bottom and the youngest layers are on the top. Because these particles settled from air or water, they were almost always horizontal. When we find sedimentary rocks that are not horizontal, either they were formed in a special way or the layers were moved by later events such as a collision of the earth's plates. Information about location and rock layers is critical for all fossils because it establishes the time and place that the plant or animal once lived.

Paleontologists take fossil finds to a laboratory to be carefully cleaned and prepared for preservation so other scientists and nonscientists can study and enjoy them. Fossils are studied and used as a comparison to categorize other fossils. Fossils can be compared with living organisms according to their similarities and differences. Some organisms that lived long ago are similar to existing organisms, but some are quite different (American Association for the Advancement of Science 1993). Examination and comparison of fossils provide data on interpretations of earth history, evolution, climate change, and extinction.

Paleontologists use evidence from fossils to formulate and test their explanations of the nature of the environment and its plants and animals of long ago. They know that all scientific ideas are tentative and subject to change and improvement. Paleontologists are therefore open to new interpretations based on fossil evidence. Students, however, may be disappointed if there is not one right answer. This simulation, adapted from an earlier version (Randak and Kimmel 2005), creates an opportunity for students to recognize the tentative nature of science and experience differences in interpretation of evidence. Students are encouraged to acknowledge such conflict and work toward finding evidence that will resolve disagreements (National Research Council 1996). They also should recognize that, although we need answers, sometimes science, exploration, and new ideas can stop when we get hung up on a preconceived notion of the right answer.

The fossils included in this lesson are from the Paleozoic ("early life") era. They are primarily from:

* the Ordovician period (the rise of corals), dating back about 500 million years

* the Silurian period (the earliest land plants and animals), dating back about 440 million years

* the Devonian period (the first amphibians crawled out of the ocean and forests began populating the earth), dating back about 360 to 400 million years ago

* the Mississippian period (the first reptiles and abundant insects), dating back about 320 to 360 million years ago

The area spanning from present-day New York, through Indiana and Kentucky, and south and west into Texas was once covered with a shallow, tropical sea and located near the equator. The shifting of the earth's plates and continents eventually moved North America to its present location.

Materials

* Letter to Paleontologists (see Figure 1), 1 per student or per student group; we suggest groups of 4

* 8 sheets of Fossil Finds (see http://education.missouristate. edu/assets/ele/fossilfinds.pdf for this set of graphics) enlarged to 8.5 inches by 11 inches or by 50 percent), 1 set of 8 sheets per group, cut on dotted lines; set aside an uncut set of 8 sheets for a teacher's key

* Sample Data Table template (see figure 2)

* 1 9-inch by 12-inch manila envelope per group

* Paleontologist's Notebook of previously discovered fossils (see http://education.missouristate.edu/assets/ele/ paleontologistnotebook.pdf for a printable version), 1 per student

* Student notebooks (spiral notebooks that students have been using with previous science activities or 5 folded sheets of blank white paper either sewn together with yarn or stapled), 1 per student

* 1 sheet of chart paper for the class, 1 blank transparency, and marker or a SmartBoard or similar projection system for your computer

* Fossil collection for the class, if available (collections with major fossil types can be purchased online for $18 to $25)

* Modern shell and coral collection for the class, if available

Categorizing fossils by shape, matrix, and physical features does not require extraordinary fossil collections. If a collection is available, use it in combination with fossil drawings to enhance the lesson. Likewise, students may have a shell and coral collection that can be used for comparing fossils with modern-day animals. Examining the evidence of the fossils can lead students to important conclusions about the nature of the prehistoric environment.

Teacher Preparation

1. Make a set of the 8 sheets of Fossil Finds for each student group. Cut the fossils from the sheets and place them in an envelope. Discard the background information and names of fossils; this is included for the teacher only. Label the envelope with a group number, name, or other identifier. Repeat for each group. Be certain that you mix up the fossils within each envelope. Each group will have one envelope of fossils.

2. Keep one set of the 8 uncut sheets of the Fossil Finds as a teacher reference. These sheets contain additional background information for the teacher and names of the fossil species in case students want to investigate further.

3. Copy the Paleontologist's Notebook pages and make a notebook for each student. (Note: The landscape format may require even- numbered pages to be flipped 180 degrees when copying front to back). Fold the sheets of paper into 8-page booklets. Procedure

The procedure follows a modified 5E format. To engage, the teacher introduces the simulation with questions and a reference guide (the Paleontologist's Notebook) for fossil identification. Then students explore by examining, drawing, and describing fossils in their own scientist's notebook. On the basis of observable characteristics, students place fossils in initial groups. The teacher moderates a "scientists' discussion" of evidence and possible classifications of fossils as students explain their emerging understandings. Students recognize the tentative nature of science and experience differences in interpretation of evidence. Students extend and clarify their new understandings as they engage in elaboration activities. The evaluation phase helps learners and teachers assess how well students understand the concepts and whether they have met the learning outcomes. There are opportunities for self-assessment and formal assessment. A detailed procedure follows (see appendix A for a quick reference).

Engage

Show students a fossil animal such as a brachiopod or a crinoid stem, if available, or a picture of an animal fossil. Many fossil photos are available on the Internet. Hold a class discussion on what students know about fossils and the scientists who collect and identify them. List students' ideas on chart paper, the overhead projector, or the projected computer screen for later reference as they respond to questions such as the following:

* What do you think this fossil is?

* How are fossils formed?

* Where can you find fossils?

* How did fossils get to that location?

* Do you think this was an animal or a plant? Why do you think so?

* Can you think of any animal or plant today that looks like this?

* How are the two organisms alike? How are they different?

* Where do you think this organism lived? When do you think it lived?

* How do you think this organism moved or ate?

* What might it have eaten? What makes you think so?

Some misconceptions may emerge in this initial discussion. As you progress through the lesson, strategically refer to this brainstormed list when the opportunity arises to challenge a misconception. Rather than immediately explaining the misconception and scientific alternative, ask questions that guide students to reconsider their notions and build more scientific ideas. For example, some students may think incorrectly that:

* All fossils represent things that are now extinct. (Actually, some fossils are the same species or are very closely related to organisms that exist today, such as brachiopods.)

* All fossil animals are dinosaurs. (Actually, more fossils are invertebrates than mammals or dinosaurs.)

* All fossils are the actual preserved animals or plants rather than parts, tracks, or castings of the organism. (Actually, "trace fossils" such as tooth marks, tracks, burrows, nests, eggs, or impressions are fossils, too.)

* "Millions of years ago" is the same as a long time ago, like when their parents were born. (Actually, "a million years ago" is 10,000 times longer than 100 years, and the average person lives fewer than 100 years.)

* Dinosaurs are fantasy creatures. (Actually, dinosaurs were real animals that existed between about 65 and 230 million years ago.)

* All dinosaurs and other organisms that form today's fossils lived at the same time. (Actually, dinosaur communities were separated by both time and geography. Different dinosaur species lived during different time periods. For example, the stegosaurus already had been extinct for about 80 million years before the appearance of the tyrannosaurus.)

Use small- and large-group discussions, notebook writing, and reference readings from trade books to provide the information and ideas for students to reflect on. See appendix B for a list of science trade books related to fossils.

Also, discuss with students how two living things may be related and have a number of common characteristics yet look different from each other. For example, both foxes and basset hounds have four legs, a tail, sharp teeth, a snout, and fur, yet they look different from each other. In fact, even among basset hounds there will be some variation in color, size, and other characteristics. The key is that related organisms have some common characteristics. Ask students:

* How might a paleontologist predict whether a fossil represents a plant or an animal?

* Did the fossil organism we have been discussing move or was it stationary? What makes you think that?

* What evidence might provide clues about where the organism lived? How did it eat? What do you think it ate?

* What do you think it looked like in real life?

* How can we tell if the fossil was the organism itself or its shell or bone? How can we tell if the fossil is the imprint of an organism?

* How can we tell which fossils are related to each other?

* How do paleontologists group fossils? How could we find out?

Inform students that their help is needed in identifying fossils recently found in a nearby rock outcrop. Hand out and read the letter provided in figure 1. Ask students what tools they might need to accomplish this task. Students may now want to know more about tools paleontologists use. This is an opportune time to discuss how paleontologists use picks, rock hammers, chisels, hand lenses, GPS (global positioning system) programs, pencils and notebooks, and computers. Paleontologists also need to understand the layers of rock in which the fossil is found to make interpretations about the fossil.

Finally, hand out and introduce students to the Paleontologist's Notebook. Tell students that they are going on a fossil hunt and will need to keep a similar notebook. Examine the notes that the paleontologist made from his or her careful observations. In small groups (or with the whole class), read the notebook. Alert students to pay attention to the scales marked next to fossil diagrams. For example, X2 means the drawing is two times bigger than the actual fossil and X0.1 means the drawing is one-tenth the size of the real fossil. Ask students to discuss questions the paleontologist might have asked as he or she studied the fossils. Discuss any vocabulary words that students do not understand. Give students the letter inviting them to join a fossil exploration.

Explore

The following steps guide students as they systematically examine the fossils and compare them to those described in the Paleontologist's Notebook from another nearby outcrop. (Italics indicate a suggested story line for the simulation.)

When you first arrive, you pitch your tent and meet with the crew foreman. He shows you four of the fossils he found the day before. You take these and return to your camp to try to identify them.

1. Divide students into groups of four. Distribute an envelope of "newly discovered fossils" and a blank notebook to each group. Students should not open the envelope until instructed to do so.

2. Ask each student to withdraw one fossil from the group's envelope. These represent the fossils the foreman found.

3. Ask students to draw their fossil in their notebook. As students are recording their observations, monitor their work by visiting each group and posing questions to focus the attention of individuals on relevant details of their specimen such as shape, texture, lines of symmetry, how the organism likely got food, or unusual features. Ask students to record notes next to their pictures of the fossil using good observation and careful note- taking skills. It is possible that every student in the class draws a unique fossil, but it is likely some will notice that students from other groups are examining the same fossil. This may lead to cross-group discussions.

4. Ask students to compare their fossil and the data they have recorded in their notebook to the records in the notebook from the other paleontologist. As you monitor student work, ask questions such as: To which group do you think your fossil is related? Why? Does anyone else in your group have a fossil that looks like it might be related to yours? What evidence supports your idea? What features seem similar? Ask questions that guide their thinking to consider the shape, symmetry, mouth (or roots), special features, and similarity to modern organisms. Invite students to discuss their findings with those of the rest of their team.

5. Tell students to record the group or phylum to which they think their fossil might belong in their own Paleontologist's Notebook.

The next day, you climb around the rocks for hours, and then one by one each of you find several really good specimens. Placing these carefully in your collecting bag, you return to your camp once again to study what you have found. You know how important it is to the museum for you to document as many details as you can in your notebook.

6. Ask each student to take out two fossils from the envelope. The group should work together to examine all of the fossils they have found so far, including those found by the foreman. It is useful to group all of the related fossils. Students should draw and describe their specimens as they did on their first entry. If time is an issue, students should choose one of the new fossils to record in their notebook.

7. Monitor student work and encourage discussion among group members as before.

Later in the afternoon, you return to the outcrop. Once again, you find additional specimens that you cannot wait to identify.

8. Ask students to withdraw the remaining (or specified number, according to your time limitations) fossils from the envelope. The group should classify these additional fossils.

9. Monitor student work by asking students what they notice about the specimens. Allow time for them to record new fossils finds in their Paleontologist's Notebooks.

10. When all fossils have been examined, recorded, and initially placed in a group, it is time for a scientists' discussion. Explain

For this part of the 5E format, hold a scientists' discussion.

1. Ask the class how they should organize the data. If no suggestions are offered, suggest they create a data table to show the categories by which investigative teams identified their fossils.

2. Ask the class how they should set up the data table. Ask questions such as: What kind of data did we record? What labels should we give column and rows to describe this data? If no ideas are offered, ask questions such as: Should we use the names of the groups to which we compared our specimens? How should we record the descriptive data that helped us make our identification? What features did we use to help us group our fossils?

3. Display a blank class data table on chart paper or large construction paper. Label the row and column headings as per appropriate student suggestions (see figure 2 for a sample data table template).

4. Ask students to "show and tell" the fossils they placed in each group and to justify their choice. Fill in class data table. First, identify the specimen numbers that students have placed in each group. Then describe the characteristics they used to identify each fossil group. For example, for tabulate corals, have students describe the evidence they found for outer covering, shape, symmetry, relative size, mouth or other opening, and other body features.

5. Discuss each animal group. Students should be encouraged to ask questions and use field guides or fossil books to learn more about each group and to verify their classifications.

6. Ask questions such as: How do these fossils provide evidence about animals that lived long ago? What characteristics do paleontologists use to group fossils? How does the location of a fossil find provide evidence for species identification? Where would you find some of the similar organisms today? What can these fossils tell us about what the environment was like long ago? What could have caused this environment to change? Why are some of these types of organisms not alive today? How can you verify that information?

7. Help students clarify their new understandings of how paleontologists classify fossils by introducing the Fossil Finds. As students share their findings, formally introduce the scientific terms for the fossil groups and other relevant vocabulary and information. Be careful not to present the "accepted" system as absolute truth, as paleontologists still disagree about many of these modern classifications.

8. Ask questions designed to help students recognize the tentative nature of science and to describe their experience of accepting differences in interpretation of evidence. Guide them to think critically and logically as they articulate relationships between fossil evidence and their own explanation. Help students listen to and respect explanations proposed by other students. Develop legitimate skepticism and science reasoning in students by encouraging questions and querying among one another (National Research Council 1996).

Elaborate

By conducting additional activities, students extend their understanding of the nature of science, learn about the plants and animals that lived long ago, and discover what fossils can tell us about the nature of the environment at that time. Students add breadth and depth to their current understanding as they engage in activities such as the following:

1. Bring in fossil field guides and student literature such as books from the National Science Teachers Association Outstanding Trade Book list (see appendix B) for students to read during literature circles. Encourage students to continue to refer to their science notebook as they discover more information about their fossils.

2. Depending on your location, local building stone may have fossils in it. Banks, city halls, and bathroom stalls often have polished limestone or even marble with fossils. Leave the rock hammers at home.

Evaluate

Although formative assessment will occur throughout this activity, the summative evaluation helps both the students and the teacher assess how well they understand the concepts and whether they have met the learning outcomes. Although traditional assessment in the form of a test may suffice, we suggest performance assessments that align with the overall instructional approach. The assessment products described below may be accompanied by a presentation to a real audience or a written explanation of the product. In additional, a self-assessment allowing students to evaluate their own learning and performance is optimum. Scoring rubrics make assessing critical content, including inquiry processes and understandings about the nature of science, more effective. (See appendix C for science benchmarks and standards to formulate scoring criteria or use your state grade-level expectations.)

Have students reconstruct the environment of a particular fossil find based on their research and investigations. For example, a marine environment could be constructed in a shoebox diorama using modeling clay, shells, corals, and feathers for the crinoid arms, licorice whips for cephalopod and horn coral tentacles, and gummy worms for worms. The back of the shoebox can have photocopies of fossils that lived on the reef. Suspend a cephalopod with fishing line to give it the appearance of a living environment. Add trilobites in the sediment of the seafloor. Picture books on today's coral reefs may help students get some idea how scientists begin to study and imagine what the environment was like millions of years ago.

Or, in line with the work of researchers, have students use the data from their notebook to "publish" (a) a description of the environment they have been exploring, (b) a report on a particular phylum of fossils, (c) a fictionalized account of a fossil hunt for a newspaper, (d) a poem about fossils, (e) an explanation of why scientists in the field must keep careful notes, or (f) a procedural piece about preparing an important fossil specimen.

Conclusion

This simulation gives students the opportunity to broaden their understanding of the nature of science and the work of scientists as they engage in active inquiry. Students learn that different kinds of questions suggest different kinds of scientific methods. They also learn that their investigations involving observing and describing fossils are a legitimate form of scientific inquiry (National Research Council 1996). Students begin to understand how we study scientific phenomena and events on which we cannot experiment. Fossils are the best evidence that can be used to answer some scientific questions.

Dear _____,

You and your team of paleontologists are needed to provide assistance to our natural history museum that has acquired an exceptionally large number of fossils recently discovered in a nearby rock outcrop. Your task is to help identify the fossils found by a road construction crew as they were excavating the rock to widen the highway. We'll meet with the construction crew foreman, who will show you the fossils he has found. He will allow you to hunt the area for additional fossils. Please bring your own tools and meet me at the outcrop.

This is not the only site in our area in which fossils have been found. A road cut near here and similar to this one has been investigated by a fellow paleontologist. She recorded notes in a notebook and it is available for your use. It could be helpful in identifying these specimens.

It is vital that you and your team keep accurate and complete records of your work. You will need to carefully draw, label, and describe each specimen and take notes about the place in which it was found. This information is essential to the museum staff as they prepare fossils for display.

We are looking forward to your arrival and your expertise in identifying these new specimens.

Sincerely,

_____

FIGURE 1. Letter to student paleontologists.

References

American Association for the Advancement of Science. 1993. Benchmarks for science literacy. New York: Oxford University Press.

National Research Council. 1996. National Science Education Standards. Washington, DC: National Academy Press.

Randak, S., and M. Kimmel. 2005 The great fossil find. http:// www.indiana.edu/~ensiweb/lessons/gr.fs.fd.html (accessed June 1, 2007).

DEBORAH A. POWELL is an associate professor of language and literacy at the University of North Carolina Wilmington.

RICHARD B. ARAM is a professional geologist, currently coordinating geoscience training for an international energy company.

ROBERTA J. ARAM is an associate professor in the School of Teacher Education at Missouri State University in Springfield.

TERRY L. CHASE is director of Chase Studio in Cedarcreek, Missouri, which designs and produces science exhibits. Copyright (c) 2007 Heldref Publications

Appendix A

5E Instructional Model Sidebar

The 5E model supports inquiry learning. Although this model appears to be linear, it is cyclical and recursive.

Engage: Creating a need to know

* Promote curiosity with discrepant event, video clip, or scenario, and questions

* Assess prior knowledge

Explore: Gathering data

* Generate ideas and explore questions

* Design and conduct investigations

* Record notes, sketches, and data tables in learning notebooks

Explain: Sharing findings and clarifying ideas

* Discuss data and articulate current understandings

* Introduce formal vocabulary and scientific explanations

* Record discoveries on chart paper and/or in notebooks

* Clarify misconceptions (may need to re-engage and explore)

Elaborate: Extending understanding

* Conduct extension activities

* Apply new concepts to a different context

Evaluate (Summative): Assessing learning

* Self-assessment

* Project or presentation

* Formal assessment

* Formative assessment occurs throughout the cycle

Note. Adapted from Learning Theory and the BSCS 5E Instructional Model by the Biological Sciences Curriculum Study (2006), Colorado Springs: BSCS Center for Professional Development Appendix B

National Science Teachers Association Outstanding Science Trade Books Related to Fossils

Dinosaur Ghosts: The Mystery of Coelophysis (1997), J. L. Gillette. New York: Penguin.

A Dinosaur Named Sue: The Story of the Colossal Fossil (2000), P. Relf and the SUE Science Team of the Field York: Scholastic.

Dinosaur Parents, Dinosaur Young: Uncovering the Mystery of Dinosaur Families (2001), K. W. Zoehfeld. Boston: Clarion.

Dinosaur Worlds: New Dinosaurs, New Discoveries (1996), D. Lessem. Honesdale, PA: Boyds Mills.

The Dinosaurs of Waterhouse Hawkins (2001), B. Kerley. New York: Scholastic.

Feathered Dinosaurs of China (2004), G. Wenze. Watertown, MA: Charlesbridge.

The Fossil Book: A Record of Prehistoric Life (1996), P. V. Rich, T. H. Rich, M. A. Fenton, and C. L. Fenton. Mineola, NY: Dover.

Fossil, Eyewitness Guide (2004), P. D. Taylor. New York: Dorling Kindersley.

Fossils: Eyewitness Handbook (1997), C. Walker and D. Ward. New York: Dorling Kindersley.

Fossil Feud: The Rivalry of the First American Dinosaur Hunters (1997), T. Holmes. New York: Messner.

Fossil Fish Found Alive: Discovering the Coelacanth (2002), S. M. Walker. Minneapolis: Carolrhoda.

Great Dinosaur Expeditions and Discoveries: Adventures with the Fossil Hunters (2003), T. Holmes and L. Holmes. Berkeley Heights, NJ: Enslow.

A Guide to Fossils (1996), H. Mayr. Princeton, NJ: Princeton University Press.

How Dinosaurs Came to Be (1996), P. Lauber. New York: Simon and Schuster.

New Dinos: The Latest Finds! The Coolest Dinosaur Discoveries! (2003), S. Tanaka. New York: Atheneum.

Searching for Velociraptor (1996), L. Dingus and M. A. Norell. New York: HarperCollins.

Secrets from the Rocks: Dinosaur Hunting with Roy Chapman Andrews (2002), A. Marrin. New York: Dutton.

SuperCroc and the Origin of Crocodiles (2002), S. Christopher. Washington, DC: National Geographic Society.

Appendix C

Science Benchmarks and Standards

Science Benchmarks

By the end of fifth grade, students should know that...

* fossils can be compared and contrasted to each other and to living organisms; some organisms that lived long ago are similar to existing organisms, but some are very different.

By the end of eighth grade, students should know that...

* thousands of layers of sedimentary rock provide evidence for the long history of the earth and of changing life forms whose remains are found in rocks; more recently deposited rock layers are more likely to contain fossils resembling existing species.

* thousands of layers of sedimentary rock also confirm the long history of the changing surface of the earth and the changing life forms whose remains are found in successive layers; the youngest layers are not always found on top because of folding, breaking, and uplifting of layers.

Science Standards

Content Standard D: Earth and Space Science

As a result of their activities in grades K-4, all students should develop an understanding that fossils provide evidence about the plants and animals that lived long ago and the nature of the environment at that time.

Content Standard D: Earth and Space Science

As a result of their activities in grades 5-8, all students should develop an understanding that fossils provide important evidence of how life and environmental conditions have changed.

Content Standard C: Life Science

As a result of their activities in grades 5-8, all students should develop an understanding that extinction of a species occurs when the environment changes and the adaptive characteristics of a species are insufficient to allow its survival. Fossils indicate that many organisms that lived long ago are extinct. Extinction of species is common; most species that have lived on the earth no longer exist.

Content Standard G: History and Nature of Science

As a result of their activities in grades 5-8, all students should develop an understanding that scientists formulate and test their explanations of nature using observations, experiments, and theoretical and mathematical models. Although all scientific ideas are tentative and subject to change and improvement in principle, there is much experimental and observational confirmation for most major ideas in science. Those ideas are not likely to change greatly in the future. Scientists do and have changed their ideas about nature when they encounter new experimental evidence that does not match their existing explanations.

In areas in which active research is being pursued and there is not a great deal of experimental or observational evidence and understanding, it is normal for scientists to differ with one another in how they interpret the evidence or theory being considered. Scientists might publish conflicting experimental results or draw different conclusions from the same data. Ideally, scientists acknowledge such conflict and work toward finding evidence that will resolve their disagreement.

Note. Adapted from Benchmarks for Science Literacy by the American Association for the Advancement of Science (1993), New York: Oxford University Press; and National Science Education Standards by the National Research Council (1996), Washington, DC: National Academy Press.

Copyright Heldref Publications Summer 2007

(c) 2007 Science Activities. Provided by ProQuest Information and Learning. All rights Reserved.