![]() ![]() Dichotomous keys consist of a series of statements with two choices in each step that will lead users to the correct identification. MaterialsĪ dichotomous key is an important scientific tool, used to identify different organisms, based the organism’s observable traits. Students will then use the pictures to model the process of creating a dichotomous key. For example, if the picture depicts an owl, accept the observation “they have eyes that face toward the front.” Do not accept the observation “they hunt at night.”įor the students’ dichotomous keys to work, the observations must be ones that the students can see in the pictures because not all students are at the same level of knowledge. Dichotomous keys are based on observations, so the instructor should encourage students to use observable characteristics, rather than behaviors. The instructor will ask the students to observe traits of the displayed organisms. Pictures should be diverse and have evident easily seen characteristics. Pictures can be projected on a smart board or overhead projector, or magnets can be placed on the back of pictures for placement on the blackboard. The instructor will find ten pictures of different plants and animals that depict the complete body of the organism rather than a partial or face shot. I can construct and use a dichotomous key based on different organisms’ characteristics.ģ0-60 minutes to review activity, collect materials, and make copies Extension: 1-2 hours to collect materials ![]() How do you use a dichotomous key and why is a dichotomous key important? What types of characteristics can be used to identify an organism? How can you identify an unknown organism? To use a dichotomous key, one must be able to make accurate observations and follow directions carefully. A dichotomous key provides users with a series of statements with two choices that will eventually lead to the correct identification of the organism. Dichotomous literally means dividing into two parts (Merriam-Webster, 2014). Most such keys are created in a dichotomous format. Classification keys are tools that provide a means to correctly identify different organisms, based on observable traits. ![]() Scientists have catalogued 1.5 million species on Earth and estimate that there might be as many as 100 million more unidentified species (Giller, 2014). Dichotomous Classification Keys: Science Students.Grade Level: Middle School: Sixth Grade through Eighth Grade Subject: Science Lesson Duration: 60 Minutes Common Core Standards: 6-8.RST.1, 6-8.WHST.2, 6-8.WHST.9, 8.SL.1, 8.SL.4, 6.EE.6, 6-8.RST.7 Additional Standards: MS-LS4-2, MS-Ls4-1 ObjectiveĪ dichotomous key is an important scientific tool, used to identify different organisms, based the organism’s observable traits.This requires a higher level of thinking and problem solving that provides excellent practice of these skills for our students. But the best part of this activity is that students are also required to develop their own dichotomous key to key out 6 different insects. My newest is called " Dichotomous Key to the Genus Smiley." In this simple key, students first learn how to use a dichotomous key. Over the years, I have developed quite a few activities that use the dichotomous classification key. I receive many requests for classification keys on different topics. But I think one of the most important uses in our classroom is the fact that they reinforce observation skills, and strengthen problem solving and critical thinking in our students. They can be used to teach scientific terms and characteristics of any type of living organism. They are also a very effective teaching tool in our science classrooms. Dichotomous classification keys are often used in field guides to help the user quickly and easily identify trees, flowers, insects, frogs, etc. ![]()
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