Brief Description:

Students will construct a prosthetic leg for a amputee figure.

Grades: 3-9+

Time: 2 hour

Concepts: prosthetic,biomedical engineering, user-centered design, range of motion

Lesson Objectives

  • Students will learn about biomedical engineering, prosthetics, and user-centered design.


  • 8.5″ tall Hardwood Mannequin
  • Crayola Model Magic
  • Krazy Glue
  • 2 Ring Terminals
  • Nut
  • Washer
  • Bolt
  • Latex Glove
  • Rubber Band
  • Ruler/Tape Measure
  • Scissors
  • Bead
  • Metal Rod (3mm in diameter)
  • Other found materials


  1. Discuss Biomedical Engineering.
    1. Biomedical engineering uses many different types of engineering techniques in the medical field. Its applications include the development of diagnostic equipment, therapeutic devices, pharmaceutical drugs and artificial limbs (prosthetics).
    2. Prosthetics are a artificial body parts used to replace limbs that have been amputated, injured, or born without.
  2. Students will be tasked with building a prosthetic leg for a transfemoral amputee. Explain that transfemoral means that the leg was cut in the middle of the femur, the bone in the thigh.
  3. The prosthetic should have a socket that allows it to be put on and taken off with ease. The knee should bend. Students may also try to make its ankle roll for full range of motion.
  4. Allow students to brainstorm, plan, and draw out their prosthetic. Have them write what materials they plan to use and how they plan to accomplish the requirements.

Extensions and Modifications:

  1. The above procedure is open-ended. If you want a more precise procedure and common products:
  2. Connect two ring terminals using a bolt, a washer, and a nut. Make sure the fit is tight, but that the joint moves smoothly. This is your knee.
  3. The most important part of your leg will be its socket. Your socket must fit snugly so that it will stay in place on the leg, but not so snugly that it cannot be removed when necessary. To make the perfect socket:
    1. Cut off the pinkie of your latex glove, and fit it over the amputee’s leg.
    2. Pull it tightly and secure it using a rubber band. The rubber band should be high enough that it will not interfere with your mold without being so high that it cuts into the hip.
    3. Cut the tip off just large enough that your knot from the end of the leg sticks out.
    4. Using Krazy Glue, attach the end of the ring terminal to the latex making the knot sit inside. The glue should stick only to the latex and not to the leg. This is important.
    5. When the glue has dried, begin putting on the Model Magic all around the leg and ring terminal to give a good transition from thigh to knee.
    6. As it dries, Krazy glue the ring terminal to the Model Magic.
    7. Leave your socket ot dry on the mannequin.
    8. When it is dry (next class period to be sure), fold the top of the latex glove over the sides and remove the socket by tugging on the glove.
    9. Try putting it on and taking it off to make sure you have a good fit.
  4. Measure the length that you will need cut for the lower leg, and make sure to consider the length that will fit into your ring terminal, and how much space you will need under it for the ankle and foot to fit. For this you should draw a diagram to scale on the engineering paper provided in pencil. When you are confident in your measurement, submit it to your instructor who will cut the rod for you (by next class period).
  5. When you have your rod to work with, cover one end very thinly with Model Magic. Put some Krazy Glue into the ring, and insert the rod into the ring. Let the glue dry.
  6. Have the doll stem into some left-over Model Magic or clay to get the size and shape of his foot. Make a foot for his new leg using this mold. To the top of the foot, for an ankle, connect a bead that will fit around the end of the dolls lower leg.
  7. Make sure your new foot will fit onto the leg and that both sides are even. When the foot is dry, glue the end of your rod into the bead, and make sure that the bead is strongly attached to the foot (this may need some glue). When the glue is dried you are done!


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