Introduction to Dichotomous Keys
Summary
In this science lab, students will investigate how to classify objects based on their similarities and differences. Students will use technical writing to explain their keys and communicate their conclusions.
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Learning Goals
1. To collectively while in cooperative groups, in order to decide how to classify various chip brands into groups and develop their first dichotomous key.
2. Develop the skill of technical writing by describing each step in the decision making process on paper.
Concepts:
1. Identify similarities and differences in a group of materials.
2. When directions are clear and precise, anyone can use them to find the same conclusions.
Vocabulary:
-Dichotomous key
-Similar
-Different
-Classification
2. Develop the skill of technical writing by describing each step in the decision making process on paper.
Concepts:
1. Identify similarities and differences in a group of materials.
2. When directions are clear and precise, anyone can use them to find the same conclusions.
Vocabulary:
-Dichotomous key
-Similar
-Different
-Classification
Context for Use
This lesson is meant for low to mid-level middle school students who have no prior knowledge in classification. This lesson is done in the lab with little intro lecture. The students should be familiar with cooperative groups prior to this lab. This lab is also a good introduction to classification of plants & animals or trees. This particular lesson involves materials that the students provide. This is an easily adaptable lesson for younger students or different subject areas.
Description and Teaching Materials
Anticipatory Set: Ask kids to "donate" the chips they brought for their lunches or after school snacks to this classroom activity. (I would give them a heads up before this class period to come prepared. In my school there will be NO issue with kids bringing in chips.) Pour all chips into a huge bowl and mix with gloved hands. Tell students they will all get a sampling after the lab. Ask for observation about the mix. How many types of chips are there in the mix? What do you think of when you look at the bowl?
Lesson: Ask students to get into their cooperative groups. Give each group a bowl-full of chips and a sheet of paper. The recorder writes down each step. Give the following directions: Separate your chips into two groups based on how they are alike. Write down how and why you separated your chips into their groups. When groups are finished ask them to separate their two groups into 4. Once again write down how and why you separated your chips into their groups. Continue to separate and explain until you have groups of completely similar groups.
Application: When all groups are finished have each group mix their chips back into their bowls. Switch bowls and directions with another group. Follow their directions to classify their bowl of chips. Did you come to the same conclusion? Were their directions clear and precise? Do you agree with the ways they choose to classify?
Take Home: Create a simple dichotomous key with a group of materials you find at home and bring key to class.
Examples:
-Tools
-Kitchen utensils
-Types of DVDs
-Bath towels
-Plants, etc.
Lesson: Ask students to get into their cooperative groups. Give each group a bowl-full of chips and a sheet of paper. The recorder writes down each step. Give the following directions: Separate your chips into two groups based on how they are alike. Write down how and why you separated your chips into their groups. When groups are finished ask them to separate their two groups into 4. Once again write down how and why you separated your chips into their groups. Continue to separate and explain until you have groups of completely similar groups.
Application: When all groups are finished have each group mix their chips back into their bowls. Switch bowls and directions with another group. Follow their directions to classify their bowl of chips. Did you come to the same conclusion? Were their directions clear and precise? Do you agree with the ways they choose to classify?
Take Home: Create a simple dichotomous key with a group of materials you find at home and bring key to class.
Examples:
-Tools
-Kitchen utensils
-Types of DVDs
-Bath towels
-Plants, etc.
Teaching Notes and Tips
1) Don't let students eat the chips that they've touched as a cooperative group. Save some of the chips from the big bowl for enjoyment after the lesson.
2) This lesson could take up to an hour so plan accordingly.
3) The day before this lesson is taught I would introduce the key vocabulary.
2) This lesson could take up to an hour so plan accordingly.
3) The day before this lesson is taught I would introduce the key vocabulary.
Assessment
Each group will hand in their individual classifications following the lesson. The at-home classification will be graded loosely. Did the student understand how to group things that are similar? Were they able to explain their thought process?
Standards
Grade 5
I. HISTORY AND NATURE OF SCIENCE
2. The student will recognize that clear communication of methods, findings and critical review is an essential part of doing science.
I. HISTORY AND NATURE OF SCIENCE
2. The student will recognize that clear communication of methods, findings and critical review is an essential part of doing science.