Fun with Taxonomy and Dichotomous Keys

Lesson Content

• Lesson Plan Template:

  General Lesson Plan

• Learning Objectives: What should students know and be able to do as a result of this lesson?

  
  

  Students will understand and apply the binomial nomenclature system of Linnaeus. They will be able to look at organisms and use characteristics, follow the steps and determine (and create) scientific binomial nomenclature names for objects and/ or silly creatures. (This is a part of Benchmark SC.6.L.15.1.)

• Prior Knowledge: What prior knowledge should students have for this lesson?

  
  

  Students should know the characteristics of living things, know that living things are called organisms, and understand that individual organisms have varying characteristics.

• Guiding Questions: What are the guiding questions for this lesson?

  
  

  As students progress through the unit the answers should become more accurate.

  At the beginning of the lesson: possible answers are given in italics

  • Why do scientists place living things in different groups? So they can organize them and name them

  Just before the video or notes on Taxonomy:

  • Aristotle first classified organisms by those that fly, those that swim and those that walk. Discuss his system with a shoulder partner. Do you think we use this system today? Why? No, this wouldn't work since some organisms like ducks can do all three and caterpillars change from walking to flying when they become butterflies or moths.

  After the video and/or notes:

  • Who is Linnaeus? Describe his classification system? Linnaeus is a Swedish scientist who first came up with a system of naming living things. He called it Taxonomy and the 7 layers go from general to specific groups: Kingdom, Phylum, Class, Order, Family, Genus, Species. He used the genus and species to give each species its own name and called this binomial nomenclature.
  • How and why did Linnaeus decide each organism needed a specific name? So that people from other countries who spoke different languages could communicate about a specific organism.
  • List the Taxonomy Levels of Linnaeus. Kingdom, Phylum, Class, Order, Family, Genus, Species.
  • Now scientists are using Domain names. Where do Domains fit in the Taxonomy levels? The domains describe cell structure and are placed above the Kingdom Name.
  • Which levels are used in binomial nomenclature? He used the genus and species to give each species its own name and called this binomial nomenclature.

  All the questions can also be discussed again at the end of the lesson.

• Teaching Phase: How will the teacher present the concept or skill to students?

  
  

  Engage: Introduce students to solving a dichotomous key. Have them add the definition of dichotomous key to their vocabulary words.

  Dichotomous key = a key used to identify an organism, usually a plant or animal, in which each stage presents descriptions of two distinguishing characters, with a direction to another stage in the key, until the species is identified.

  1. Have students solve a key on types of candy. Note that this key uses terms with which students are not familiar and so they can't just find the candy's common name but must follow the steps.
  2. I have provided directions on the candy key which should be read orally. Here is more background for the teacher. Teach them to choose one item or organism shown on the page. Read the first set of paired statements and choose the one that best describes the first organism's characteristics. Follow to the next step indicated and read that set of statements. They must continue to refer to the same item or organism and follow the directed path until they come to a name for that organism. Then they will start over with another organism or picture on the page. Students must always start and read and choose between the first set of paired statements. Confusion can exist if an organism is #6, they may want to start with the 6th step. Be sure to supervise to prevent confusion. It may be best to solve the first candy together. Then have them continue as a group or individually and then compare with their team.

  Next Activity: Direct Instruction

  1. Find and show a video on Taxonomy developed by Linnaeus. Have students write notes during the video and then discuss them afterwards. If no video is available, or even if one is, you may go on to step 2.
  2. Have students peer read in their textbook or an article you have found or written and printed out. (see attached) Students will copy notes.

• Guided Practice: What activities or exercises will the students complete with teacher guidance?

  
  

  Students will apply taxonomy by continuing to solve dichotomous keys, but this time on living things. (There may be one in your textbook, or I have provided an example here. You may also search your text or the internet for other choices.)

  Tell them that all keys are different and one dichotomous key cannot be used for all organisms since not all have the same characteristics. Also every once in a while you may encounter a key with sets of more than 2 statements from which to choose.

  For additional practice, have the class create a dichotomous key for the people in the class or their shoes. This makes it fun and gives them the idea that you divide into 2 main groups and then subdivide each group until each person or shoe has just one "scientific 2-word name."

  Have each student check their own papers in class.

  Students who are still confused can receive another paper to practice individually or work with a partner or a student who can guide them. Observe their progress to verify understanding.

• Independent Practice: What activities or exercises will students complete to reinforce the concepts and skills developed in the lesson?

  
  

  Create a dichotomous key and give scientific names to creatures or organisms. Have them work in 2, 3, or 4 person teams.

  • The teacher can provide pictures of silly creatures (I have provided one), or have students draw or cut out pictures from magazines or print them from the internet.
  • Students will color and cut out the pictures and create a dichotomous key and give each organism a scientific name using binomial nomenclature. They will have to start with large groups and subdivide until each creature is alone and then give it a 2-word scientific species name. They will have to write out or type their paired statements.
  • Then students will need to paste the pictures and their paired statements on a large 12 x 18 inch paper. Have them make an answer key on another paper and paste it to the back of their key. Here the teacher should make sure they have as many scientific names as creatures and advise them if there is confusion.
  • When the group feels theirs if perfect, they will switch with another group and each group will follow the key to determine organism names.
  • If groups are unable to figure out the key due to incorrect clues, then they must give it to the teacher to verify the problem and then back to the team who created it to fix it or start over.
  • After they have solved and written down the species names for the other groups' key, then have them check their answers with the answer sheet created by the authors.
  • The receiving team gives a grade to the writing team and then the writing team should give an accuracy grade to the receiving solving team.

• Closure: How will the teacher assist students in organizing the knowledge gained in the lesson?

  
  

  Students will be given a quiz. (See attached) (Answers are from the notes given previously)

• Summative Assessment

  
  

  A quiz will be given in which students will be asked to create a few steps of a dichotomous key.

  Some of the questions can be changed to multiple choice if desired.

• Formative Assessment

  
  

  Teacher will observe the pairs or groups as they work on solving the dichotomous keys and as students create their own.

• Feedback to Students

  
  

  Students will judge their progress when another group solved their dichotomous key and when they solve the dichotomous key created by another group. Can the creators recognize problems and correct them? How accurate and user-friendly was their key for users?