LESSON 7:

FOOD MATTERS

INTRODUCTION

We often think of food webs on land. There 

are interesting food webs in the ocean, too. 

This lesson explores how scientists know 

that matter flows from food to the animals 

eating it, then links to the idea that this 

transfer of matter means that plastics in the 

ocean are a reason for concern. 

LESSON SUMMARY

In this lesson, students learn about basic 

fish anatomy and use data to determine 

what happens to the food that an animal 

eats once it is in their bodies. Using this 

information, students consider what 

happens when an animal eats microplastics 

and share ways to keep plastics out of the 

ocean. 

68

OBJECTIVES

• Students will be able to describe how 

matter flows through food webs in the 

ocean.

• Students will be able to explain the 

impact of plastic in the ocean on the 

animals that live there.

ESTIMATED TIME

60 minutes. If you would like to break this 

lesson up over multiple days, consider 

pausing between steps 8 and 9. 

STANDARDS ADDRESSED

Science (NGSS): 5-LS2-1. Develop a model 

to describe the movement of matter among 

plants, animals, decomposers, and the 

environment.
69

OCEAN LITERACY 

PRINCIPLES

5 The ocean supports a great diversity of 

life and ecosystems.

6 The ocean and humans are inextricably 

interconnected. 

FOCUS QUESTION

What happens to the “stuff” that makes up 

food when an animal eats it? What happens 

if an animal eats something it should not? 

MATERIALS

• Fish Anatomy handout, one per student

• Fish Anatomy handout, one copy to 

display (optional)

• Different-colored pens or pencils

• What Happens to Food? master, one 

copy to display

• Ocean Food Web master, one copy to 

display

• NOAA resource on the Great Pacific 

Garbage Patch, see Preparation section

PREPARATION

Read through the lesson in advance. In 

step 11, there is a choice of resources to 

use with your students. Determine which 

resource(s) you would like to use with your 

students. If you choose to use the video, 

make sure you have the materials you 

will need to show the video in class. If you 

prefer to use one or both of the readings, 

consider if you will print copies or display 

them for students to read. 

FACILITATION

Step 1. Start the lesson by asking students 

what they think happens to the food that 

they eat. They may share different ideas, 

including our bodies using it for energy, the 

food leaving the body as waste, it getting 

“digested,” or others. Accept all answers at 

this point, paying attention to those ideas 

that may represent a partial understanding. 
70

Step 2. Distribute the handout, Fish 

Anatomy, to students. You may also wish 

to display a copy of the handout so you 

can point out the different labeled parts of 

the fish. Share with students that scientists 

wanted to understand what happens to 

food when an animal eats it. Scientists 

have a way to mark the food that fish eat so 

they can trace where that food ends up. Tell 

students to think of it as soaking something 

in glow-in-the-dark paint so that the paint 

soaks into every part of the object. These 

markers stay on food particles, even when 

they break down.

Step 3. Tell students that they are going to 

have a chance to think about the different 

results a scientist might see, depending on 

what food gives to our bodies. Give each 

group one of the following scenarios and 

ask them to use a colored pen or pencil 

to draw small circles to indicate where 

scientists might find the labeled food in 

the fish if the scenario is correct. Consider 

writing each scenario on a small piece of 

paper to give to students so the group 

can continue to refer to it. If other ideas 

came up in Step 1 that would be good for 

students to think about, you may wish to 

include those. 

For your own information as you facilitate 

this lesson, the third statement about 

food breaking down into smaller pieces 

and becoming part of the body is correct. 

It represents what the scientists found in 

their investigations. The other statements 

are based on common conceptions that 

students may have. 

• We eat food to fill our stomachs so we 

can be strong. 

• We eat food to give us energy. Energy 

moves out of food particles from the 

digestive tract into the body. 

• We need food to grow and maintain our 

bodies. Food breaks down into smaller 

pieces, which move into the body and 

become part of it. 

• We need vitamins from food. The 

vitamins move out of food particles 

from the digestive tract and into the 

body.

• We eat food to help us stay strong. Food 

breaks into smaller pieces of protein 

which then move into the muscles to 

build them up.

Step 4. As students work, circulate around 

the room to make sure students are on the 

right track. Once groups have had a chance 

to finish drawing where they think the food 

would be found in the fish. The following 

table is to support you in helping the 

students.
Step 5. Ask each group to share the 

scenario they worked on and what they 

drew on the fish. If more than one group 

had the same scenario, have them compare 

what they drew on the fish. 

Step 6. Have students begin a legend for 

their fish figure by drawing a small circle in 

the color they have been using and writing 

“prediction from scenario” next to it. Then 

ask them to choose a different colored pen 

or pencil for the next part of the activity. 

Step 7. Divide students into new groups so 

that each group has one student who was 

exploring each scenario. If you did not add 

any additional scenarios, each group will 

have 5 students. Have the students sit close 

to each other to form the new groups.

Step 8. Tell students that you are going to 

share what scientists found about what 

happens to food. Display the master, What 

Happens to Food? Ask students to take 

a minute to observe the representation 

quietly. Have them add what they see to 

their fish graphic by drawing triangles with 

the new color of pen or pencil. Ask them to 

add to the legend to show that the triangles 

represent what scientists found. Then 

have students talk with their groups to see 

which scenario it seems to match. Students 

should find that the image matches that 

food breaks down and becomes part of the 

body. Hold a class discussion about their 

ideas, pointing out that the food became 

part of all the different tissues in the body. 

Describe how food breaks down and then 

becomes part of the matter—the particles—

that make up the body of the animal that 

ate the food. 71

SCENARIO WHERE LABELED FOOD WOULD BE

We eat food to fill our stomachs so we can 

be strong.

Students should draw small circles in the 

stomach and/or along the whole digestive 

system

We eat food to give us energy. Energy 

moves out of food particles from the digestive tract into the body.

Students should draw small circles within 

the digestive system.

We need food to grow and maintain our 

bodies. Food breaks down into smaller 

pieces, which move into the body and become part of it.

Students should draw small circles 

through the whole fish body.

We need vitamins from food. The vitamins 

move out of food particles from the digestive tract and into the body.

Students should draw small circles within 

the digestive system.

We eat food to help us stay strong. Food 

breaks into smaller pieces of protein which 

then move into the muscles to build them 

up.

Students should draw small circles in the 

muscles on the diagram. They may also 

draw them in the digestive system to show 

the labeled food after the fish ate it and 

before it broke down.
Step 9. Show students the master, Ocean 

Food Web. Share that this web shows 

several of the relationships between 

animals that live in the ocean. When 

animals eat food, they get energy and 

matter from the food. Have students 

choose one food chain from the web, 

starting with plankton. Explain that this 

is one set of animals that get energy and 

matter from each other in order—the same 

way a grasshopper gets energy and matter 

from grass and then a bird can get energy 

and matter from the grasshopper. The bird 

does not eat the grass directly, but the 

grass, grasshopper, and bird make a food 

chain. Ask them to draw the food chain 

they chose. Encourage them to draw the 

animals fairly large because they will need 

to add to them.

Step 10. Tell students to imagine that the 

plankton is all labeled to see where its 

matter goes. Ask them to draw colored 

triangles to show that the plankton is 

labeled. Then ask them to add in the label 

where they think they would eventually 

see it. After giving students some time, 

hold a class discussion to make sure 

students understand that the matter from 

the plankton would be incorporated not 

only into the next animal, but that once 

that animal became food, the label would 

become part of the third animal as well. 

Each of the three animals should have 

colored triangles when students have 

completed their drawings. 

Step 11. Share with students that one of 

the things scientists have found in recent 

years is a lot of plastic in the ocean. Show 

students the NOAA video, Trash Talk: What 

is the Great Pacific Garbage Patch (https://

marinedebris.noaa.gov/videos/trash-talkwhat-great-pacific-garbage-patch-0)

If you are unable to play the video for your 

students, consider using one or both of the 

following NOAA resources. 

• What is the Great Pacific Garbage Patch? 

• How Big is the Great Pacific Garbage 

Patch?: Science vs. Myth

If you use these resources, orient students 

to the map to show that the continental 

United States is on the right side of the 

graphic and Hawaii is visible just west of 

the label, “Eastern Garbage Patch.” Have 

students use a reading strategy, such as 

popcorn reading or read-summarize by 

paragraph, to share the information with 

the class. Share that plastics have been 

found throughout the ocean, not just in 

these patches.

Step 12. Remind students that many 

animals live in the ocean. Others migrate 

through different parts of the ocean, such 

as humpback whales making seasonal 

migrations from Alaska to Hawaii. Highlight 

the last sentence of the reading that 

animals may ingest, or eat, plastics. Have 

students think about what this means for 

food chains and food webs, based on what 

they have been learning. Then have them 

discuss their ideas in their small groups. 

Step 13. Hold a class discussion about 

what may happen when animals eat 

plastics. They should come to understand 

that the plastic may become part of their 

bodies and may be passed on to other 

animals in the food web. Ask students to 

discuss ideas of how they can help keep 

plastics out of the ocean. The end of the 

video in step 11 focused on prevention 

and you can use those ideas to guide the 

discussion. 

72
73

EXTENSION

NOAA’s Marine Debris Program has many resources for teachers and students at https://

marinedebris.noaa.gov/activities-and-curricula . Consider expanding this lesson to focus 

students on other aspects of marine debris and its impacts using the resources there. 

The NOAA Ocean Today Video Collection: Every Full Moon - Trash Talk is a series of 15 videos 

discussing marine debris in more detail: what it is, where it comes from, how it harms animals, 

activities students can do in the classroom, and what students can do on their own to address the 

problem.

Lesson 7 NOAA References

• NOAA Marine Debris Program video Trash Talk: What is the Great Pacific Garbage Patch

(https://marinedebris.noaa.gov/videos/trash-talk-what-great-pacific-garbage-patch-0)

• NOAA Ocean Service, What is the Great Pacific Garbage Patch? (https://oceanservice.noaa.gov/

facts/garbagepatch.html)

• NOAA Office of Response and Restoration, How Big is the Great Pacific Garbage Patch? Science 

vs. Myth (https://response.restoration.noaa.gov/about/media/how-big-great-pacific-garbagepatch-science-vs-myth.html)
FISH ANATOMY

74
WHAT HAPPENS TO FOOD?

75
OCEAN FOOD WEB

76