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Alan Alda in Scientific American Frontiers









 
Teaching Guide
Hands On, Minds On
Planetary Problem Solving
Self Propelled Learning
Quiz
image of bony hands

Human hands are an incredible adaptation in structure and function. Their unique and effective anatomy permit a remarkable range of grasping, holding, and manipulating options. Comprised of 27 separate bones, each hand has played an essential role in the shaping of both tools and human history.

In Handmade Humans, you observed how laboratory tools are used to record images of the hands' range of motion. By studying these electronic recordings, scientists can make inferences about the movements and abilities of early humans.

In this activity, you'll also have the opportunity to make your own inferences about the structure and function of our hands. You will also get the chance to uncover a relationship between hand actions and recorded points of contact.



 

OBJECTIVE
This activity page will offer:

  • understanding of human hand structure and function
  • appreciation of the complexity and range of hand motions
  • exploration in which to apply critical observation skills

PART 1 - INFERRING STRUCTURE

MATERIALS

  • pencil
  • sheets of scrap paper

PROCEDURE

  1. Place your hand down in the center of a blank sheet of paper. Spread out your fingers.
  2. Use a pencil to carefully draw the outline of your spread fingers and palm.
  3. Remove your hand from the tabletop and examine its structure. Straighten and flex your fingers. Twist your wrist and palm. Observe the movement and limitations of the hand's structure. From these actions, can you infer the shape and placement of the 27 bones that comprise the hand?
  4. As you gain confidence in understanding this unseen anatomy, sketch the most likely shape, size and placement of the hand bones on your drawing.
  5. To see how you did, log onto the x-ray Web site offered at the end of this activity. Or reference The Visual Dictionary of the Human Body, published by Dorling Kindersly, pp. 26-27.

TENDONS & LIGAMENTS
Extend your forearm, holding your palm face down, and wiggle your fingers.

  1. How does this action affect the surface of your forearm?
  2. How far up the arm can you detect movement beneath the skin?
  3. What are ligaments? What are tendons?
  4. Is the action you observed a result of tendon or ligament movement?
  5. What in the biological advantage of having tendons move finger bones?

PART 2 - DISTINGUISHING GRASPS

MATERIALS

  • Water-based finger-paint
  • paint brush
  • sheets of scrap paper
  • pencil
  • broomstick
  • small ball
  • large ball
  • scrap newspaper
  • Although not necessary, graph paper can be useful tool in this activity. Using grid boxes, students can determine the grasp contact area by counting blocks or by comparing the geometry of the different grasps.

PROCEDURE

  1. Work with a partner.
  2. Protect your workspace with a covering of scrap newspaper pages.
  3. Carefully open a jar of finger-paint. One member of the team takes a dab of paint. Using a paintbrush spread the dab over the entire surface of a pencil.
  4. Once the pencil has been fully coated with a thin layer of paint, hold the pencil by its eraser end. The other team member grips the pencil as if to write with it.
  5. Hold the pencil firmly and don't let it move around. Paint will transfer from the pencil to the points of contact with your hand.
  6. Once the paint has been transferred, make a print of your coated fingers and hand.
    NOTE:
    You'll have to roll each finger individually just as if you were taking a fingerprint. You may also have to roll your hand to transfer the paint from higher points of contact. It is important that each of the "rolls" be placed in the relative position of that finger.
  7. Label this print "writing grasp". Clean your hands and exchange roles.
  8. Spread a dab of paint over a portion of a broomstick. Have one teammate hold the uncoated part of the stick, while the other person grasps the painted section with one hand as if it were a tennis racket.
  9. Once the paint has been transferred, make a print of your coated fingers and hand.
  10. Label this print "stick grasp". Clean your hands and exchange roles.
  11. Continue making contact prints of the grips and grasps used to hold the assortment of objects supplied by your instructor. Remember to use only a small amount of finger-paints and to spread it only over the area that is most likely to make contact with the hand and fingers.

QUESTIONS

  1. Compare and contrast the different prints. Which print recorded the largest surface area of contact? Which print recorded the smallest area of contact?
  2. What can you infer from the area of hand contact?
  3. How would you identify the use of opposable digits?
  4. Create an organization system that could be used to classify these prints. What print properties would this scheme be based upon?

EXTENSIONS

WRITING GRASPS

  1. Compare and contrast the way different students hold pencils.
  2. How many different types of grips can you distinguish?
  3. What characteristics would you use to describe this grasp?
  4. What differences, if any, exist between the pencil holding grips of left-handed and right-handed students?

HAND SIGNALS

  1. Log onto this site and printout the American Sign Language fingerspelling alphabet. Or visit the library and check out Signing Illustrated: The Complete Learning Guide (Flodin, Mickey).
  2. Compare and contrast the signs. How is the hand's dexterity critical to this mode of communication? Which fingerspellings involve movement?
  3. Learn how to sign your name and the name of one classmate (don't tell them you are learning their name). Once you have learned both signs, put the printout away.
  4. When asked by your instructor, sign the name of the classmate whose name you learned to sign. How many students can infer and understand the name you are signing from the small bit of the sign language they learned?

MULTICULTURAL CONNECTION
While growing up, you develop and perfect grasps that are dependent upon your social surroundings. Many of us first learned to eat using a knife and fork. But, have you ever tried to eat using chopsticks? If so, how does this grasp compare to holding a fork? Which grasp requires more flexibility and control? Which grasp can apply a firmer grip to the eating utensil? How does the thickness of a chopstick effect its ease of use? Design a strategy of inquiry that would compare the eating effectiveness of different widths of chopsticks.

FEET FIRST

Although other primates may have feet that can grasp and manipulate objects, our own feet lack this ability. That's because our feet are adapted for their primary role, walking. Primates that walk with their hands have limited hand movements. Can you infer why?

WEB CONNECTION

Interactive x-ray of hand bones
Especially valuable as a resource to part 1.

Hand transplant
News article with links on first US

Comprehensive site on hand anatomy
University of Arkansas for Medical Sciences- however, it does present information and images of cadaver dissections.


ANSWERS

"Hands-On, Minds-On" and "Self-Propelled Learning" were contributed by Michael Dispezio, a Massachusetts-based science writer and author of "Critical Thinking Puzzles" and "Awesome Experiments in Light & Sound" (Sterling Publishing Co., NY).

Academic Advisors for this Guide:
Neil Glickstein, Science Department, Waring School, Glouchester, MA
Corrine Lowen, Science Department, Wayland Public Schools, Wayland, MA
Suzanne Panico, Science Department, Fenway High School, Boston, MA

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