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Organization of Living Things

Organization of Living Things

Introduction: In order to keep all living things organized, a system of classification has been developed so that scientists know exactly where to find every living organisms. This system, called taxonomy, organizes living things by common characteristics. 

The original classification scheme was proposed by Aristotle. He said that all living things were either plants or animals. Further, they were then classified by where they lived. Birds would be air animals, fish were water animals, and lions were land animals. THe same held true for plants. 

As you can imagine, this was slight confusing. After all, birds do fly, but they also hunt for food on the ground. In the 18th century, a Swedish botanist named Carolus Linnaeus devised a system that is still in practice today. He put organisms into similar categories based upon their similar traits. Prior to Linnaeus' work, organisms were classified be their observable traits. For example, birds and butterflies were considered relatives because they can both fly. Since the discovery of DNA and the advent of molecular testing, it has been possible to better see the relationships between organisms and fine tune the system of classification.

To make things even clearer, Linnaeus invented a naming system that eliminates confusion when scientists are discussing living things. He assigned, based upon common traits, a specific naming structure for each organism.

Linnaeus proposed the following scheme for every organism. It goes from the most generic group to the most specific.
Kingdom
Phylum
Class
Order
Family
Genus
Species

It is possible for more than one organism to belong to the same family (such as cats) but only one type of organism can have a particular species (such as Felis domesticus - the common house cat). Every organism has a genus and species, a system Linnaeus called binomial nomenclature.

Directions for this Lesson: Answer the practice questions and then watch the video to learn more about taxonomy and how organisms are classified.


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