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.
Extinction is when all members of a particular group die. Most often, we use it to discuss animal species. Many fear that the tiger is headed for extinction because of development and hunting. People are still trying to figure out what caused the extinction of the dinosaurs: many think it was because of an asteroid. When people cut down rain forests, it can lead to the extinction of many species. Although extinction can be natural or unintended, the word can also mean forced, planned killing.