Starting at the first couplet, choose which of the two alternatives best suits an object or thing, and proceed to the couplet number or answer indicated by that choice. The number of things being considered is reduced at each successive step in the key so that by a process of elimination the correct determination is made.
Example objects to identify: apple tree, water-lily, fir tree, dandelion, astroturf, seaweed. Download Worksheet 1. Download Lesson Plan. This type of key is not hard to use, but makes more sense when students undertake the process of making one before using it.
The instructor will model the process before students begin work on their own keys. After the demonstration, students will first make a Branching Key using a picture of an organism of their choice.
Once the Branching Key is completed, students will convert it into a written dichotomous key. The end product will be a poster displaying the student pictures, along with their written dichotomous keys.
After modeling the process, direct students to take out the ten pictures that they collected for their project. Students will then go through the same process to create a dichotomous key unique to their pictures. Students will make a poster with a written dichotomous key and pictures on the front and their branching keys rough draft on the back.
After grading, students should display their dichotomous keys around the room for all students to observe. Students will be given different unknown organisms with keys for identification and will work through the identification process. Sources of keys: internet or textbooks.
Instructors may also wish to use field guides for local areas, using pictures of animals or plants that students might see in their backyards or parks. Step 3: Divide the specimens. Step 4: Divide the specimen even further. Step 5: Draw a dichotomous key diagram.
Step 6: Test it out. What is the importance of a dichotomous key? A dichotomous key is an important scientific tool, used to identify different organisms, based the organism's observable traits. Dichotomous keys consist of a series of statements with two choices in each step that will lead users to the correct identification. What are the characteristics of a dichotomous key? The word dichotomous means branching into two.
A single characteristic is considered at a time. Two contrasting statements are put forward to describe the characteristics in such a way as to separate the organisms. This continues until all the organisms have been identified. What is another word for dichotomous? Words related to dichotomous binary, amphibian, diploid, bifurcate, divided, zigzag, split, branching, tined, angled, bifurcated, branched, furcate, divaricate, bilateral, dual, amphibious, bicameral, bigeminal, binal.
What does a dichotomous key look like? A dichotomous key is a way of identifying specimens based on contrasting statements, usually about physical characteristics. By drawing a series of contrasts, you are able to narrow down the specimen until you can correctly identify it.
Dichotomous keys are often used in the sciences, such as biology and geology.
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