Tortoises--Bones on their Backs


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


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. 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. Find out about how turtles are being affected by changes in the Earth’s climate, such as rises in sea temperatures.

3. Here are some tips for completing your sculpture. Create an armature from crumpled aluminum foil. Build up the vault of the shell. Shape the neck, tail, and four legs.

4. Choose 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 adding washable marker color to Model Magic and kneading to blend. Plan for a textured, realistic look for your magnificent creature.

5. Build extremities. 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 you work, use Crayola School Glue to attach them.

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. Construct upper shell (carapace). 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 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. Cover your craft area with newspaper. Brush on the glaze. Air-dry.

12. Label and exhibit your 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.

Safety Guidelines

Adult supervision is required for any arts & crafts project. Observe children closely and intervene as necessary to prevent potential safety problems and ensure appropriate use of arts and crafts materials. Some craft items, particularly beads and buttons, are potential choking hazards for young children. Avoid use of such small parts with children younger than 3 years. Craft items such as scissors, push pins and chenille sticks may have sharp points or edges. Avoid use of materials with sharp points by children younger than 4 years. Read all manufacturers' safety warnings before using arts and craft supplies.

Crayola Modeling Materials including Crayola Model Magic®, and Model Magic Fusion™, Crayola Air-Dry Clay, and Crayola Dough—

  • Keep away from open flames. Do not use to make candleholders, hot plates, trivets, or other similar objects that will be used or placed near fire and other heat sources.
  • Do not put in an oven, microwave, or kiln.
  • Do not make into vessels/containers that will hold unpackaged food.
  • The use of modeling material to make items that look like food is discouraged for children younger than age 5 to avoid their confusion with real food.
  • Unless sealed with a water-resistant glaze, do not make projects exposed to or immersed in water, such as boats or outdoor bird feeders. They would disintegrate when exposed to moisture.
  • Crayola Dough—contains gluten (wheat flour) as an ingredient.
  • Crayola Air-Dry Clay, Crayola Model Magic and Model Magic Fusion are gluten-free. However, they are produced on the same machinery as Crayola Dough which does contain gluten. Although the machines are cleaned prior to the start of each production run, there is a slight possibility that trace amounts of gluten from Crayola Dough may be present in the other modeling compound products. For information regarding specific ingredients or allergic concerns, please call our Consumer Affairs department at 1-800-272-9652 weekdays between 9 AM and 4 PM Eastern Standard Time.

Scissors—ATTENTION: The cutting edges of scissors are sharp and care should be taken whenever cutting or handling. Blunt-tip scissors should be used only by children 4 years and older. Pointed-tip scissors should be used only by children 6 years and older.


  • Explore how a turtle’s shell affects its life, dictating the way that it breathes and moves. Find out why some turtles have a flatter shell. Study the "shell" of a leatherback turtle. How have turtle shells changed during 200 million years? Prehistoric turtles were 10 feet long (3 meters) and weighed 4,000 pounds (1814 kilograms).
  • Look at the three types of turtles: tortoises (who are land animals that sometimes go in water), terrapins, and sea turtles (both live in the sea and lay eggs on land). There are eight species of sea turtle, more than 100 types of tortoises, and 180 terrapins. What are their similarities? Their differences? Are there any places where turtles are not found?
  • Find out why balloon releases, including strings, are a danger to turtles and other marine animals.
  • Delve into the role that turtles play in the various creation myths of Native American tribes such as the Iroquois, Huron, and Hopi. Find out about the Hindu belief that the universe is balanced on a turtle shell.
  • Thirty-six species of turtle are endangered. Investigate the reasons for this including egg harvesting, adult capture, and habitat destruction. Learn why repopulation is not a quick and easy solution. Find out what changes are being made to help resolve this environmental preservation issue.
  • Assessment: Does the sculpture accurately exemplify the three parts of the shell and the turtle’s body parts? Is the coloration accurate? Are colors and various forms of modeling techniques used to create realistic texture and dimension?

Related Lesson Plans

Lesson Plans

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crayola supplies
  • Arts & Crafts Brushes
  • Model Magic®
  • No-Run School Glue
  • Pointed Tip Scissors
  • Washable Markers
household supplies
  • recycled newspaper
  • aluminum foil
  • container(s) of water



  • Grades 4 to 6
  • Grades 7 to 12


  • Science
  • Visual Arts


  • Multiple Sessions


  • Students gather information about tortoises including details about body parts.

  • Students research the effects of climate change on turtles’ lives.

  • Students realistically reproduce textures and colors of turtles using modeling techniques to create 3-D sculptures that illustrate their findings.


Research Canada Standards
Research UK Standards
Research U.S. Standards