Embryonic Development - Evidence for Evolution

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Objective

SWBAT analyze displays of pictorial data to compare patterns of similarities in the embryological development across multiple species to identify relationships not evident in the fully formed anatomy.

Big Idea

Students explore embryonic development across species as evidence for evolution.

Engage

10 minutes

I start this lesson by showing students the following picture of embryos across different species.(MS-LS4-3. Analyze displays of pictorial data to compare patterns of similarities in the embryological development across multiple species to identify relationships not evident in the fully formed anatomy.)  

 

1.  Students are asked to compare and contrast the embryos in particular focusing on physical appearance. Students can use a Venn Diagram to complete this task.

 

2.   I follow this by asking student the following question: "What do you think is the reason for the similarities between all four embryos?"  The answer that I'm looking for is that the similarities are due to all 4 species descending from a common ancestor.  

3.  Students conduct a Think-Pair-Share - When asked to consider an idea or answer a question, students write their ideas on paper (think). Each student turns to another student nearby and reads or tells his or her own responses (pair, share). This is an oral exchange, not a reading of each other's papers. (SL8.1 - Engage effectively in a range of collaborative discussions (one-on-one, in groups, teacher-led) with diverse partners on grade 7 topics, texts, and issues, building on others’ ideas and expressing their own clearly.)  

Explore

25 minutes

In this section of lesson students explore embryos across species Using the interactive Guess the Embryo from NOVA. (MS-LS4-3. Analyze displays of pictorial data to compare patterns of similarities in the embryological development across multiple species to identify relationships not evident in the fully formed anatomy./SP4 - Analyzing and Interpreting Data)  

1. Students are required to match a series of embryos to their adult forms, and then watch each creature develop during a portion of its early growth.

2.  As students explore each embryo students are required to draw each embryo (1st picture shown) and write a brief description of each.  

3. In the last part of this activity I have students conduct a small group discussion on the following prompt - "Based on your drawings and description of embryos what two species do you feel are more closely related?" (SL.8.1Engage effectively in a range of collaborative discussions (one-on-one, in groups, teacher-led) with diverse partners on grade 6 topics, texts, and issues, building on others’ ideas and expressing their own clearly./CCC - Patterns - Graphs, charts, and images can be used to identify patterns in data.) 

- To facilitate small group discussion I have students use a RoundRobin* with AllWrite Consensus*:

    1. Teacher poses a problem to which there are multiple possible responses or solutions, and provides think time.
    2. Students take turn stating responses or solutions
    3. After reaching consensus, students each record each answer on their own paper.

* We are a Kagan school, so I use the Kagan version of these strategies.

Explain

10 minutes

In this part of the lesson I show students the following video titled Embryological Evidence for Evolution.  


As students watch video they are required to answer the following questions:

1.  Who was Ernst Haeckel?  How did his work contribute to Charles Darwin's Theory of Evolution?

2.  What did Haeckel's drawings show?

3.  All animals come from a common __________________.

4.  What was the problem with Haeckel's drawings?

5.  One of the main points of Haeckel's drawings is that the more closely related embryo forms shared a more recent common ancestor.  Going back to your embryo drawings what two shared a more recent common ancestor?

6.  Another important idea from Haeckel's drawings that scientists have held up over the years is that within closely related forms, earlier stages will be more similar than late stages.  Do your embryo drawings agree with this idea?

Elaborate

10 minutes

In this section of the lesson students read an article on Comparative Embryology courtesy of Coloring Concepts Inc. New York: HarperCollins, 2001.   

To access text students use Writing in the Margins as a strategy, specifically the clarify strategy. I explain this strategy more fully in the reflection.

Evaluate

5 minutes

Students complete an Exit Slip, where they are required to write a scientific explanation on how embryo development across species is evidence for evolution. (SP6 - Constructing Explanations)