5-8 Classification Keys

Section 1: Welcome to the Activity

Focus Question

How is a classification/dichotomous key used? Why is it important to classify organisms?

Activity Synopsis

Students will practice using a classification/dichotomous key to identify shoes. Students will then use a variety of mollusk shells (or their pictures) from the South Carolina coast to demonstrate the identification and classification of living things using a classification/dichotomous key.

Objectives
The learner will be able to:
  • Successfully use a classification/dichotomous key
  • Understand the complexity of classification and taxonomy

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Section 2: Standards

6th Grade:  6.S.1A.2, 6.S.1A.6, 6.S.1A.8, 6.L.4A.2, 6.L.4B.1
7th Grade:  7.S.1A.2, 7.S.1A.6, 7.S.1A.8, 7.EC.5A.1
8th Grade:  8.S.1A.2, 8.S.1A.6, 8.S.1A.8

* Bold standards are the main standards addressed in this activity

2014 Sixth Grade Performance Indicators

6.S.1A.2  Develop, use, and refine models to (1) understand or represent phenomena, processes, and relationships, (2) test devices or solutions, or (3) communicate ideas to others.

6.S.1A.6  Construct explanations of phenomena using (1) scientific evidence and models, (2) conclusions from scientific investigations, (3) predictions based on observations and measurements, or (4) data communicated in graphs, tables, or diagrams.6.S.1A.8  Obtain and evaluate informational texts, observations, data collected, or discussions to (1) generate and answer questions, (2) understand phenomena, (3) develop models, or (4) support hypotheses, explanations, claims, or designs. Communicate observations and explanations using the conventions and expectations of oral and written language.

6.L.4A.2  Develop and use models to classify organisms based on the current hierarchical taxonomic structure (including the kingdoms of protists, plants, fungi, and animals).

6.L.4B.1  Analyze and interpret data related to the diversity of animals to support claims that all animals (vertebrates and invertebrates) share common characteristics.

2014 Seventh Grade Performance Indicators

7.S.1A.2  Develop, use, and refine models to (1) understand or represent phenomena, processes, and relationships, (2) test devices or solutions, or (3) communicate ideas to others.

7.S.1A.6  Construct explanations of phenomena using (1) scientific evidence and models, (2) conclusions from scientific investigations, (3) predictions based on observations and measurements, or (4) data communicated in graphs, tables, or diagrams.7.S.1A.8  Obtain and evaluate informational texts, observations, data collected, or discussions to (1) generate and answer questions, (2) understand phenomena, (3) develop models, or (4) support hypotheses, explanations, claims, or designs. Communicate observations and explanations using the conventions and expectations of oral and written language.

7.EC.5A.1  Develop and use models to describe the characteristics of the levels of organization within ecosystems (including species, populations, communities, ecosystems, and biomes).

2014 Eighth Grade Performance Indicators

8.S.1A.2  Develop, use, and refine models to (1) understand or represent phenomena, processes, and relationships, (2) test devices or solutions, or (3) communicate ideas to others.

8.S.1A.6  Construct explanations of phenomena using (1) scientific evidence and models, (2) conclusions from scientific investigations, (3) predictions based on observations and measurements, or (4) data communicated in graphs, tables, or diagrams.8.S.1A.8  Obtain and evaluate informational texts, observations, data collected, or discussions to (1) generate and answer questions, (2) understand phenomena, (3) develop models, or (4) support hypotheses, explanations, claims, or designs. Communicate observations and explanations using the conventions and expectations of oral and written language.

South Carolina College and Career Standards for ELA
Communication (C) – 6-1.1, 6-1.2, 7-1.1, 7-1.2, 8-1.1, 8-1.2

Common Core ELA Standards
Speaking/Listening – 6.1, 6.2, 6.4, 7.1, 7.2, 7.4, 8.1, 8.2, 8.4
Language – 6.1, 7.1, 8.1

Section 3: Background

Key Points will give you the main information you should know to teach the activity.

  • Taxonomy is the classification of organisms based on shared characteristics.
  • Classification keys, or dichotomous keys, can be used to identify organisms. Some are very simple and some are very complex.
  • Mollusks are a group of invertebrate animals including gastropods (snails), bivalves and cephalopods (squid, octopus) found in the Phylum Mollusca

Detailed Information gives more in-depth background to increase your own knowledge, in case you want to expand upon the activity or you are asked detailed questions by students.

Taxonomy is the classification or grouping of organisms based on shared characteristics. By grouping organisms, relationships can be studied, patterns in nature can be identified and information can be organized for all to use. With conservation being of increased value, understanding the diversity of an area is very important in making informed decisions and taxonomy is very important is discovering diversity.

In taxonomy, there are 8 main levels or categories, called taxa (singular taxon). The categories in order of most general to most specific are Domain, Kingdom, Phylum (plural phyla), Class, Order, Family, Genus and Species.

A classification key or dichotomous key is a tool which contains pairs (or occasionally triplets) of descriptive characteristics which enable choices to be made about a particular organism, eventually leading to its specific identity. The term “dichotomous” literally means “divided into two parts”. 

An important aspect of educating children is helping them to develop an interest in and appreciation for the world around them. This not only provides tools for exploration and learning on their own but also helps to develop a conservation ethic to enable them to become better decision-makers and more inclined to protect natural resources. There are many popular versions of field guides published for the various groups of organisms (as well as some nonliving things), many of which include dichotomous keys. Enhancing interest in the natural world, combined with the knowledge of how to use such a tool further empowers children to be lifelong learners and conservation-minded citizens. 

Mollusks will be used for this activity for several reasons.  Most children find the calcium carbonate shells of most mollusks interesting and often choose to collect them from coastal areas.  Also, the particular mollusks that were used to create this activity are common and relatively easy to find along most of South Carolina’s coastlines. 

The Phylum Mollusca consists of invertebrate organisms with soft bodies, most of which make calcium carbonate shells using special glands and minerals from the water in which they live.  Most taxonomists agree on classification of seven classes of mollusks, with the two primary shell-producing classes being Class Gastropoda, gastropods (snails and snail-like mollusks) and Class Bivalvia, bivalves (clams, oysters, mussels, etc.). Another popular class is the Cephalopods because they include the squid and very intelligent octopus.

Some species of mollusks are managed by the South Carolina Department of Natural Resources due to their use by individuals and commercially as seafood. It is important for people to understand that a mollusk shell should only be collected from the beach when found empty (snail is dead) and then only if used for some purpose. It’s not ok to take lots of shells from the beach and then place them in a box in a garage to never be looked at again. Shells can be used by other animals for shelter (hermit crabs) and they also break down over time and make sand. By taking them off the beach, they cannot do that. It is ok though to collect a few of your most treasured beach finds to display in your house or garden.

Section 4: Procedures

Part 1 – Warm up exercise

Part 2

Part 1 – Warm up exercise

Preparation: Cut 1 set of shoes per pair of students. Would be great if the picture sets could be laminated so they could be used again from year to year.

  1. Begin class by reviewing what taxonomy is and how important it is to understand the organisms of the world. They provide us with food, protection, medicines, oxygen and more.
  2. Let students know that scientists have created classification keys (or dichotomous keys) to help identify organisms. The keys use characteristics of the organisms to guide them to a single species.
  3. Next the students will practice using a classification key to identify different shoes.
  4. Have students work in pairs. Give each pair a set of shoe pictures, a Classification Key for Shoes and a Shoe Classification Worksheet.
  5. Working with their partner they should identify each shoe to number. Shoes are lettered, the answer to each will be a number.

*Note: If you find that 23 shoes is too many, have each group work on 4-5 shoes and as a class they will get them all done.

Part 2

Preparation: Place 1 shell in each lab station with a Mollusk Classification Key (A-G)

  1. Review part 1’s activity by reminding them what a classification/dichotomous key is and how it is used to identify objects or organisms.
  2. Discuss the terms “gastropod” and “bivalve” and their meaning.
  3. Place students in groups and have each group start at a different station.
  4. Make sure each student has a writing utensil and a Classification Worksheet.
  5. Practice how to use the key by having one student read the first pair of characteristics aloud. Have each group of students decide which of the 2 characteristics best describes their shell.
  6. Explain that they are to work through the key, choosing the correct characteristic in each pair and following the instructions beside it to identify their mollusk shell. They will identify 7 shells (A-G).
  7. Now, have them move from station to station until they have identified all 7 mollusks.
  8. Go through the answers as a class to make sure each group identified them correctly.

*Note: If you have enough shells you could give each group a set of shells or pictures to identify instead of setting it up as stations.

  • How long do you think it takes for scientists to come up with a classification key?

  • What happens to a classification key when a new species is identified?

Section 5: Assessment

Give each student a Classification Assessment Worksheet and have them create their own classification/dichotomous key. Before turning them in, have them trade keys with a classmate to see if they can follow the instructions.

Scoring Rubric out of 100

For creating a classification key that is correct, clear and easy to follow 100 points
For creating a classification key that is mostly correct 80 points
For creating a classification key that is not easy follow 70 points
For not trying or not finishing 0-69 points

Section 6: Cross-Curricular Extensions

STEAM Extension
Have students design and build a dichotomous key mobile using these animals (snail, oyster, butterfly, fish, duck, owl, alligator, dolphin and mouse). They will have to balance the mobile and make sure each arm goes down to one animal.

STEAM Extension
Have students create 5 different organisms out of materials in the classroom and then create a dichotomous key for identifying them.

Section 7: References

Teacher Reference Books

Raven, Peter H. and George B. Johnson. Biology: Sixth Edition. McGraw-Hill Companies. New York. 2002.

Teacher Reference Websites

How Stuff Works

http://science.howstuffworks.com/life/biology-fields/taxonomy-info2.htm

Website for basic taxonomy information as well as a list of each Kingdom and the Phyla that are within each.

National Center for Biotechnology Information

http://www.ncbi.nlm.nih.gov/taxonomy

Database for the taxonomy of most organisms

Online Activities

Clemson Extension

http://www.clemson.edu/extfor/publications/bul117/

Great tree identification activity using leafs with a dichotomous key.

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