Iris folding is a paper craft technique that involves folding strips of colored paper in such a way to form a design.The center of the design forms an iris â a shape reminiscent of the iris diaphragm of a camera lens.istory [edit]. Iris folding originated in Holland, where early craft people made their designs using patterned paper cut from the inside of envelopes. Today, crafters use any light weight paper, such as scrapbook paper, origami paper, wrapping paper, the inside of envelopes or pages of magazines. Ribbon is also used.
Extinction is the disappearance of a previously learned behavior when the behavior is not reinforced. In this lesson, learn more about extinction in operant conditioning and test your knowledge with a quiz.
Just as birth and death are natural events in the life of an individual, the rise and fall of species are natural processes of evolution. The elimination of a species from Earth is called extinction. Extinction often occurs when a species as a whole is unable to adapt to a change in its environment.