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Tortoises--Bones on their Backs

Turtles are found in almost every part of the world. Students investigate what we can learn from these fascinating creatures and create a science project that will WOW everyone!

  • Grade 4
    Grade 5
    Grade 6
  • Multiple Lesson Periods
  • Directions

    1. A tortoise’s shell is a living, integrated part of the animal similar in nature to human hair or nail. A tortoise’s shell, its skeleton, is made of 50 bones, a modified vertebrae, and bony skin plate. When the shell is damaged, it bleeds. Amazingly, tortoise shells sometimes regenerate to repair the damage.
    2. Provide opportunities for students to look at photographs of tortoises, especially ones such as the Indian Star and the Asian Flower Back. Notice the patterns and colors found on these ancient species. Invite students to investigate how turtles are affected by changes in the Earth’s climate, such as rises in sea temperatures.
    3. Once students research is complete, they will be using Crayola Model Magic® to create a tortoise sculpture based on their research findings. After covering their work space with recycled newspaper, students create an armature from crumpled aluminum foil. Build up the vault of the shell. Shape the neck, tail, and four legs.
    4. Students select several Crayola Model Magic® colors to make a realistic replica of one species of tortoise—background, highlights, and marbleized colors. Mix original hues by blending two or more colors, or Ultra-Clean Marker color to white Model Magic and kneading to blend. Plan for a textured, realistic look for this magnificent creature.
    5. To build the extremities, students cover all the foil extremities with a Model Magic background color such as black. Form small cones for toes (turtles walk on their toes). Attach toes to legs. If Model Magic pieces dry while working with it, use Crayola School Glue to attach pieces.
    6. The legs and tail of a tortoise may have two differently textured surfaces. To cover the underneath side, form small balls of Model Magic in a color different from the background. Flatten these balls on the background. For the top side of the legs and tail, roll out some compound with a marker barrel. Snip small wedge-shaped plates with scissors. Starting at the tip of the foot near the toes, lay down a line of wedges. Overlap more wedges in an alternating pattern to form armor. Intersperse various colors of wedges.
    7. Shape the neck and head with a beaked nose, open mouth (but don’t extend the tongue because turtle tongues can’t protrude out of the mouth), and hooded eyes on either side of head. Apply similar colors and modeling techniques used for the legs and tail to texturize the head.
    8. Assemble lower shell (plastron). Run a flat ridge of background color down the underside of foil from the neck to the tail (these are the cartilaginous bones that evolved from collarbone and ribs). Next, shape flat wedges (osterderms or fused plates) and fit these around bottom of the armature along the center ridge, with smaller wedges starting at the front and larger ones towards the rear of the tortoise. For the outer scales (scutes), marbleize the background color with another color like yellow. These elements give the tortoise its color and texture. Attach to the plates.
    9. To construct upper shell, or carapace, students build wedges similar to those made for the plastron only with more dimension and shades of colors. To form the vault of the top shell, radiate wedges out from a center circular plate. Again layer marbleized shapes to enhance texture and realism.
    10. Connect the parts. A bony structure called the bridge joins the upper and lower shells. Mold the underneath part of the bridge. Design the top side part of the bridge similarly to main shell. Attach shells to these. Use more modeling material to reinforce joints where legs, neck, and tail connect with bridge. Your foil armature now should be totally encased in Model Magic compound. Air-dry the sculpture for at least 24 hours.
    11. Glaze the tortoise. Mix equal amounts of glue and water to make a glaze to strengthen the figure and give it that shiny tortoise look. Students check that their work spaces are still covered with recycled newspaper. Brush on the glaze. Air-dry.
    12. Label and exhibit the magnificent creation in a science fair, art show, or other major event. Offer details about the turtle’s habits, habitat, and prognosis for future survival.
  • Standards

    LA: Read and comprehend informational texts, including history/social studies, science, and technical texts, at the high end of the grade level text complexity band independently and proficiently.

    LA: Produce clear and coherent writing in which the development, organization, and style are appropriate to task, purpose, and audience.

    MATH: Represent and interpret data.

    SCI: Ask questions to clarify evidence of the factors that have caused the rise in global temperatures over the past century.

    SCI: Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations.

    SS: Identify and use various sources for reconstructing the past, such as documents, letters, diaries, maps, textbooks, photos, and others.

    SS: Describe and speculate about physical system changes, such as seasons, climate and weather, and the water cycle.

    SS: Examine the interaction of human beings and their physical environment, the use of land, building of cities, and ecosystem changes in selected locales and regions.

    SS: Explore causes, consequences, and possible solutions to persistent, contemporary, and emerging global issues, such as pollution and endangered species.

    SS: Identify examples of laws and policies that govern scientific and technological applications, such as the Endangered Species Act and environmental protection policies.

    VA: Intentionally take advantage of the qualities and characteristics of art media, techniques, and processes to enhance communication of experiences and ideas.

  • Adaptations

    Possible classroom resources include: Turtles & Tortoises (Beginning Vivarium Systems) by Russ Case; Popular Tortoises (Advanced Vivarium Systems) by Phillippe De Vosjoli; Tortoises: A Beginner's Guide to Tortoise Care by Andrew Highfield & Nadine Highfield; Desert Tortoises: The Library of Turtles and Tortoises by Christopher Blomquist; Lonesome George, the Giant Tortoise by Francine Jacobs; Lonesome George: The Life and Loves of the World's Most Famous Tortoise by Henry Nicholls.

    Encourage student groups to explore how a turtle's shell affects its life, dictating the way it breathes and moves. Students investigate why some turtles have a flatter shell and how this affects their lives.

    Students investigate how the evolution of turtle shells over the past 200 million years. Prehistoric turtles were 10 fee long (3 meters) and weighed 4,000 pounds (1814 kilograms). What caused their down-sizing?

    Invite groups of students to research the three types of turtles: tortoises, terrapins, and sea turtles. There are eight species of sea turtle, more than 100 types of tortoises, and 180 terrapins. What are their similarities? Differences?

    Hindus believe that the universe is balanced on a turtle shell. Students investigate this belief. What is it based on?

    Nearly 40 species of turtle are endangered. Students investigate reasons for this classification, which include egg harvesting, adult capture, and habitat destruction. Investigate what changes are being made to help resolve preserving turtle habitats.


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