Authentic Lessons for 21st Century Learning

How EGG-ceptional Are We? (Middle School)

Evolution: Embryonic Development

K20 Center, Alexandra Parsons, Mariah Warren | Published: August 4th, 2022 by K20 Center

  • Grade Level Grade Level 7th, 8th
  • Subject Subject Science
  • Course Course Biology I
  • Time Frame Time Frame 150 minutes
  • Duration More 2-3 class periods


Students will investigate the similarity of reproduction, embryonic development, and DNA sequences to illustrate the indirect evidence for evolution. This lesson is adapted for a middle school class.

Essential Question(s)

How do we decide what to believe about evolutionary claims?



Students listen to the storybook An Egg Is Quiet then discuss observations from the book.


Students attempt to sort embryo images into similar groups.


Students use a second card sort and analysis questions to draw conclusions.


Students analyze a graph to draw conclusions about similarities between organisms.


Students answer open response questions to collect their thoughts and ideas.


  • An Egg Is Quiet by Dianna Aston

  • Lesson Slides (attached)

  • Student Version Embryo Card Sort (attached, one per group of 2-3, cut out)

  • Teacher Version Embryo Card Sort (attached)

  • Explain Card Sort (attached, one per group of 2-3, cut out)

  • Analysis Questions (attached; one half-sheet per student)

  • Animal Embryo Development Graph (attached; one per student)

  • I Used to Think, but Now I Know Handout (attached; one half-sheet per student)

  • Sticky notes


Open the attached Lesson Slides. Go to slide 3 to introduce the essential questions and then to slide 4 to introduce the objectives to students.

Go to slide 5. Read the picture book An Egg Is Quiet by Dianna Aston to students. If you do not have access to the book, show students the following "An Egg Is Quiet" read-aloud video on YouTube. While you read, students should use the I Notice/I Wonder strategy to write down observations, important details, and questions they think about as the teacher reads.

Allow students to look back through the book if they need to revisit it. In pairs, have students share what they've written and revisit the book (or copies of pages of the book) to either reinforce the observations they made or to revise them. Also, use this time for students to discuss the questions they wrote and see if rereading the book answers the questions or if further investigation is needed.


Go to slide 6 and pass out the 'Set A' Card Sort embryo cards (letters at the bottom) from the attached Student Version Embryo Cards to groups of two or three students. This activity is done using the Card Sort instructional strategy. Prompt students to group together embryos that they think are similar. There are no duplicates, so each is a unique animal, but possible categories could be mammals, reptiles, amphibians, etc. Some students will think these are similar animals but in different developmental stages. Try to leave it open-ended and leave the prompt as 'group what you think is similar together' if possible. When students are done, have them do a modified Gallery Walk, where students write why their group decided the card groupings on sticky notes as category headings. The groups then rotate and read the other groups' ideas. When a full rotation through has happened, give time for students to decide if they want to change their original groupings or not.

Taking the idea further, pass out the 'Set B' Card Sort embryo cards from the same document to each group, so that both Set A and Set B are together. Give the prompt again to create groups. Students will probably understand that the idea is to pair the embryo with the developed animal, but try not to give it away.


Let students keep the Card Sorts for reference during Explain and some of the Extend.

Go to slide 16 and pass out the attached Explain Card Sort cards with a few of the stages of a chicken embryo and a mouse embryo. Either display the prompt or verbally share the prompt: "There are two sets. Separate the two sets, then put each set in order." Allow students to work on this in pairs.

Once students think they have completed the prompt, distribute the attached Analysis Questions. Using the strategy Inverted Pyramid, have students share their answers with partners, creating a shared answer that represents both of their answers. Then, partners join together to make a group of four, sharing again, this time with a focus on the statements generated. Once the groups of four construct a shared statement, each group shares their statements with the whole class, with the teacher writing them on the board for everyone to see. From here, explain to students how all organisms develop in the same stages, called Carnegie Stages, but they go through those stages at different rates and different sizes. Explain how the organ shapes will be different for different animals, but the stages themselves are all the same.


Go to slide 21 and distribute the attached Animal Embryo Development Graph to each student. Have them construct the chart and answer the questions. Allow them to use this data to support their products in the Evaluate section.


Go to slide 22 and pass out a half sheet from the attached I Used to Think... But Now I Know document to each student. Give about 5 minutes for students to reflect on what was presented to them and record what they used to think about embryos and fetal development compared with what they now know. Have students share their responses with a partner, then turn their responses in as an Exit Ticket.