Applied Science - Science and Math (6C)
Lab 

   
OBJECTIVES:
  • Comparing and contrasting different fibers.
  • Recording observations.
VOCABULARY:
  • fabric
  • fiber
  • synthetic
MATERIALS:

Students use a microscope to look at fabric and their fibers.


Cotton Fibers

BACKGROUND:

Introduce this lab by telling students that all their clothing is made of fibers which are thin, thread-like pieces of plant, animal or man-made (synthetic). However, most fibers are polymers as discussed in the Pre Lab.  The principle use of fibers is in the manufacture of textiles, stuffing for mattresses or upholstery, brushes, and paper.  Fibers can be broadly classified as coming from plant, animals or manufactured by humans. 

Draw the following chart on the board to illustrate some fiber or fabric types and where they come from.

TYPE

PLANT ANIMAL SYNTHETIC

cotton 

X

 

 

wool

 

X

 

polyester

   

 X

nylon

   

X

jute

X

   

angora

 

X

 

Fabrics are made by interconnecting or joining of fibers by the process of weaving, knitting, or felting (like paper).   Fibers are sometimes combined or mixed to make  varieties of fabric.  For example, a shirt label that reads "75% cotton, 25% wool" means that each strand of thread or yard of fabric there  is 3/4 cotton fiber blended with 1/4 wool fiber.

In Forensic Science the study of fibers helps to locate who may have been at a crime scene.  Detectives may find hair fibers from humans and analyze it for DNA or other properties that can help find a suspect.  Minute fibers from a rug can be found on people's clothing, which can be traced to a carpet in a house or car.

PROCEDURE:

  1. Reinforce that most fibers are polymers.  The first exercise has the students use the magnetic ball and rods to make a repeating chain of one or two patterns.  This would be a polymer, which repeats the original "mer".  The molecule is chemically not the same as a chain of the same molecule. They should come up with a similar design as below.
  2. Students should  look at several samples of different fabric and see how the fibers are woven together.  Students should observe the fabric and record what they see under  the microscope.  Make sure they do not confuse the weave of the fibers with the actually fibers.  To view the fiber, direct students to the fringes of the piece of cloth. 
      
  3. This exercise is not only an introduction to investigating science, but also for students to learn about different fibers.  Emphasize with students that scientists have to learn about different subjects by observing and recording information before they can actually formulate a question about that subject.  Refer students to  the "Guide to Fibers"  to help identify the fibers.
      
  4. You can easily add on to this lab by having students  identify what kind of fabric they are wearing.  You may want to make a list of the different types of clothes students have on and try to “group them.” Most of their clothes will probably be cotton and polyester blend. You may want to point out that  fabrics made from silk or rayon  are usually expensive.

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