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Oysters – The Tale of Two Shells

Activity Summary

Students learn the anatomy of an oyster’s shell and the role of the 

shells in protecting the oyster.

Learning Objectives

Students will be able to:

• Label the exterior parts of the oyster.

• Explain the importance of the oyster shell in protecting the 

animal.

Essential Question

What role do oyster shells play in protecting the oyster?

Background Information

Oysters, a type of mollusk, are animals that have a soft body 

surrounded by two hard shells. They live in coastal waters like the 

Chesapeake Bay. Some oyster species live grouped together on oyster 

reefs.

Historically, oysters in North America have served many purposes for 

the inhabitants of coastal areas. Native Americans found oysters to be 

an abundant and reliable source of food, and they used the shells as

K-12 Oysters in the Chesapeake Bay

Grade Level: 

Grade 1

Teaching Time: 

2-30 minute sessions

Materials:

• 2-4 oyster shells per 

group*

• At least one shucked 

oyster

• Chart paper

Per Student

• ruler or standard unit 

of measure object,

such as a Unifix cube, 

paper clip or penny 

• blank paper (1 sheet)

• pencil and/or markers

• Oysters on the Half 

Shell activity sheet (p. 

5) 

• scissors

• glue

• various items 

described in Part 2 

below

*Teacher Note:

Oyster shells have very 

sharp edges. Acquire 

shells that have been 

worn and have smooth 

edges to avoid injury.
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tools, weapons, ornaments and even currency. Today, oyster harvest and cultivation provide 

significant economic value to regional coastal communities. 

In addition, oyster reefs provide habitat for other species, including some commercially 

important species. They filter the water and increase water clarity by extracting organic and 

inorganic particles from the water column. In turn, this increase in water clarity promotes the 

growth of submerged aquatic vegetation, which also provides habitat for other organisms.

However, the loss of oyster reefs in the United States during the past 200 years has been 

significant. Due to over-harvesting, increased sedimentation, pollution, invasive species and 

disease, the amount of oyster harvest has decreased dramatically—reducing income and jobs 

for workers in the oyster industry. But just as important, the loss has removed habitat for other 

animals and plants and decreased water quality in estuaries and coastal waters.

The NOAA Restoration Center is working to involve citizens and scientists in projects to restore 

this valuable resource and to understand more about the ecology of oysters, oyster reefs and 

their functions in coastal waters. For more information, visit http://www.habitat.noaa.gov/

Key Words

Bivalve - An aquatic mollusk that has a compressed body enclosed within a hinged shell

Filter - A device that separates or removes matter

Hinge - The joining point of the two valves of a mollusk shell at the anterior end. 

Mollusk - An invertebrate that has a soft unsegmented body and lives in aquatic habitats and 

often has a shell. 

Oyster - Bivalve mollusk with rough irregular shell sometimes eaten as a delicacy and may be 

farmed for food or pearls

Engagement 

Give each student, or small group of students, two oyster shell halves to investigate for several 

minutes. Have the students draw and write, if appropriate, their observations on Student 

Response Sheet 1 (What Do I See?). Have the class share their observations and record on a 

class chart.

Exploration

Part 1:

Tell the students an animal lives inside the oyster shells. Have them manipulate their two shells 

to determine how the two halves of the oyster shells work together to protect the animal. Have 

students share their ideas.
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Part 2:

1. Show the students a live oyster. Either shuck it or have a pre-shucked oyster available. 

2. Have the students observe and touch the mollusk. Note the softness of the mollusk’s 

body. Ask the students if it would be easy for the mollusk to be injured or eaten by prey 

without a shell. Why or why not?

3. Ask the students to explain how the shell protects the oyster. Give each group some 

type of delicate item such as a Pringles potato chip.

4. Explain to the students that the item is delicate and can easily be eaten or destroyed. 

5. Ask students how they might protect the chip from being eaten or destroyed. 

6. Give the pairs or small groups of students various items (such as small milk cartons, 

cardboard, cotton balls, string, tape, etc.) and have them create a structure that would 

protect the chip if dropped. 

7. Have them test their apparatus by dropping it from three feet in the air. Let them work 

to improve their structure if needed and repeat the tests.

Explanation

Part 1:

1. Explain to students that oysters are mollusks that live near coastal shores and that they 

are not only a source of food, but also help to filter water.

2. Explain that oysters have two shells that fit together and are called bivalves (bi means 

two). The two shells connect by a hinge. Have students compare and contrast each side 

of the oyster shell. Explain that the rough side is the outer shell and that the smooth side 

is the inner shell. 

3. Discuss the properties of the shell. Include color, texture, and size. How do these 

properties help the oyster survive? The outside color (mottled grey) blends in with the 

bottom of the bay (camouflage). The rough texture on the outside gives plants and other 

animals a place to hook on to grow, adding more camouflage. The smooth texture on 

the inside is nice for the soft body of the oyster. The hinged shell allows the oyster to 

open to feed and to close up tight to protect itself. They oyster grows bigger, adding shell 

each year.

4. Have the students place a shell, outer shell up, on a blank piece of paper and trace the 

outer edge. Have students label it “outer shell,” 

5. Ask the students to measure the height of the shell (measure height the “tall way”) in 

whole numbers using a ruler, Unifix cubes, or a standard unit of measurement, such as 

paper clip or penny and record. Height is measured from the anterior to the posterior. 

6. As a class, create a data chart with each oyster’s height. Create a graph from the chart.

Part 2:

1. Send students on a gallery walk to observe each structure that they developed in the 

Exploration section of the lesson. 

2. Ask volunteers to share their structure and process. Have them explain why they chose 

certain materials to make the structure, how the structure responded to their tests and 

what modifications they made the structure and why.
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3. Relate their structure back to the structure of the oyster shell and compare/contrast 

parts of the oyster structure with the student made structures.

4. Discuss with the students any patterns they notice in the structures their classmates 

built. For example, all the students may have used a hard outer layer (milk cartons or 

other harder materials), soft inner layers for padding (tissue, pom-poms, etc.), and 

similar ways to keep the outer layer closed (tape, string, etc.)

5. Have student draw and label, if appropriate, their final structure using Student Response 

Sheet 2 (My Structure).

Extension

1. In their journals, have students write and/or illustrate what they have learned about 

oysters.

2. Read, Olly the Oyster Cleans the Bay by Elaine Ann Allen, or another story describing 

how oysters filter water. Ask the students to write a story about an oyster and how it 

helps to clean the water and the bay. 

3. Explain that oysters grow in groups (reefs) and once they mature, they do not move. 

Have students explain the benefits of being a free-swimming and sessile (stationery) 

organisms.

4. Make a paper oyster (see p. 5). 

Evaluation

Formative: 

1. Class discussions and participation

Summative: 

1. Student Response Sheet 1 (What Do I See?)

2. Student Response Sheet 2 (My Structure)
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Education Standards

Three Dimensional Learning

Disciplinary Core 

Idea(s)

1-LS1.A Structure and Function

All organisms have external parts. 

Different animals use their body parts in 

different ways to see, hear, grasp 

objects, protect themselves, move from 

place to place, and seek, find, and take 

in food, water and air. Plants also have 

different parts (roots, stems, leaves, 

flowers, fruits) that help them survive 

and grow. (1-LS1-1)

How Standard is Addressed

Students learn about the 

external body parts of oysters

and their functions.

Science/Engineering 

Practice

Constructing Explanations and 

Designing Solutions

Constructing explanations and designing 

solutions in K–2 builds on prior 

experiences and progresses to the use 

of evidence and ideas in constructing 

evidence-based accounts of natural 

phenomena and designing solutions.

• Use materials to design a device 

that solves a specific problem or 

a solution to a specific problem. 

(1-LS1-1)

Students learn about the 

structure of the oyster and 

how the shell protects the 

mollusk inside the shell. 

Students then apply that 

information to constructing a 

structure to protect a soft 

object.

Cross – Cutting 

Concepts

Structure and Function

The shape and stability of structures of 

natural and designed objects are related 

to the function(s).

Students learn about the 

external body parts of oysters 

and their functions. They 

apply the same concepts to 

constructing a structure to 

protect a delicate object.

Common Core Standards

Ties to Common 

Core

SL1-1b

Build on others’ talk in conversations by 

responding to the comments of others 

through multiple exchanges

SL1.1c

Ask questions to clear up any confusion 

about the topics and texts under 

discussion.

Students discuss the 

construction of their 

structures, respond to 

questions about the 

structures, and 

compare/contrast their 

structure with those of an 

oyster.
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SL1-5

Add drawings or other visual displays to 

descriptions when appropriate to clarify 

ideas, thoughts, and feelings.

Students make drawings of 

their structures.

Maryland Environmental Literacy Standards

Ties to MD 

Environmental 

Literacy Standards

Standard 7: Environment and Society

Topic A: Environmental Quality

Indicator: Investigate factors that 

influence environmental quality.

Students learn that the 

Chesapeake Bay is part of the 

environment and pollution is 

diminishing the quality of the 

water.

Additional Resources

Web Resources

Protecting Our Water Resources: Student Activities for the Classroom

Water and educational activities for Kindergarten through Ninth Grade

http://www.stormwater.ucf.edu/toolkit/vol3/Contents/pdfs/Student%20Activities/student_activities.pd

f 

Olly the Oyster

Visit this website for coloring pages, puzzles, word searches, crafts, and more. 

http://www.ollytheoyster.com

Sammy’s Corner: An Oyster Recycling Program

Visit this site for some great teacher resources all about oysters. Download a poster, curriculum 

guides, and a wealth of oyster activities. 

http://oysterrecycling.org/sammys-corner/

Book Resources

Allen, Elaine Ann. Olly the Oyster Cleans the Bay. Tidewater Publishers, May 1, 2008. ISBN-10: 

0870336037.

Tate, Suzanne. Pearlie Oyster: A Tale of an Amazing Oyster. Nags Head Art, Inc., June 1, 1989. 

ISBN 10: 0961634472.
Name

What Do I See?

Draw the oyster shells you have. 

Add as many details as you can.

The Tale of Two Shells—Student Response Sheet 1

1

What did you observe about your oyster shells?
Name

My Structure

Draw a picture of your structure. 

Add as many details as you can.

The Tale of Two Shells—Student Response Sheet 2

1

Describe your structure.