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Amphibians, Reptiles, and Fish Lesson

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I am a Christian. I was an 8th-grade American History teacher. I am currently a freelance writer, public speaker, & homeschooling mom of 9.

Measuring the fish before we dissect it

Measuring the fish before we dissect it

This is part 3 of a 5 part hands-on unit study on Animals and Zoology. Peel your "skin" like a reptile, dissect a fish, make origami jumping frogs, compare amphibian and reptile eggs by feeling tapioca and grapes, and more as you study Amphibians, Reptiles, and Fish! My lessons are geared toward 3rd-4th grade level children and their siblings. These are lessons I created to do with a weekly homeschool co-op. We meet each week for 2 1/2 hours and have 11 children between the ages of 0-13. Use these fun lessons with your classroom, family, after school program, camp, or co-op!

Inspecting a turtle, which is a coldblooded vertebrate

Inspecting a turtle, which is a coldblooded vertebrate

Introduction, Review, and Animals in Exodus

1. Stretch. Pray.

2. Review classification. If desired, sing first verse of "Six Kingdoms" & "Invertebrates" songs from previous lessons. (Find the links to the previous lessons by going to the section toward the bottom of this page titled "Ready for the next lesson?".)

3. Read about 10 plagues using some of Exodus from Egypt by Mary Auld. (Alternatively, you could read the passage from the Bible.)

  • Ask the children to name all the cold-blooded vertebrates or invertebrates mentioned during the plagues. (The staff changes into a reptile [snake]. Fish die from the blood in the Nile River because of the blood. Amphibians [frogs] fill the land.)

YOU WILL NEED: Exodus from Egypt by Mary Auld or other book on the 10 plagues

Imitating mouth brooder fish using jellybean "eggs"

Imitating mouth brooder fish using jellybean "eggs"

Fish Overview

4. Quickly discuss the differences between endothermic & ectothermic (warm-blooded & cold-blooded) animals.

5. Read most of Fish: Finned and Gilled Animals by Suzanne Slade.

  • While reading, have children open and close their mouths repeatedly to get air, just like the fish do.
  • Briefly mention mouth brooders and have children each hold a small handful of "eggs" (jellybeans) in their mouths without biting or swallowing them just like mouth brooders carry eggs in their mouths. Don't swallow your fish eggs!
    • Most fish leave, but not all. The male jawfish is a mouth brooder, holding the eggs in his mouth until they hatch...and sometimes even after that if they sense danger. Let's try that.
    • Pass out about 10 jelly beans to each child to hold in their mouths while you continue reading. Don't eat your babies!
    • A female seahorse lays her eggs in a pouch in the male's abdomen.
    • A small fish is a fry.
    • Some fish give birth to live younger, so they're called livebearers.
    • You can now stop pretending to be that jawfish. You can chew up and swallow your baby fish eggs.

YOU WILL NEED:

  • a bag of jellybeans (at least 100 jellybeans)
  • Fish: Finned and Gilled Animals by Suzanne Slade or other book giving an overview of fish

Book to read for activity 5: Fish

Using a balloon and water to demonstrate how fish bladders work

Using a balloon and water to demonstrate how fish bladders work

Fish Bladders

6. Fish have 2 special organs.

  • Some also have electric organs near their tail with specialized muscle or nerve cells with cells called electrocyles that can be used for communication, stun prey, or deter predators. Who can name a fish with electric organs? (electric eel, torpedo, electric catfish)
  • Most fish have a swim bladder that lets them stay suspended in any depth of water? It is kind of like this balloon?
  • Demonstrate how fish bladders work. God designed fish to have a swim bladder that fills with air when they want to rise in the water, and it lets all the air out when they want to sink in the water. Demonstrate using a balloon and a large bowl of water. Blow up the balloon, and show how the filled "swim bladder" lifts the "fish" up near the surface of the water. Let the air out to show how that allows the fish to sink lower. The air is lighter than water, so it helps the fish to rise when the swim bladder is full.
  • People have used a similar design in submarines.
  • Which fish doesn't have a swim bladder (bottom dwellers like flounder)

YOU WILL NEED:

  • a balloon (not inflated)
  • a bowl of water
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Observing a live fish

Observing a live fish

Fish Observation

7. (Optional) Spend a few moments observing a fish swim.

  • What do you notice about it?
  • How many fins does it have? Which ones does it move the most? What do you think each of the fins does?
  • How frequently does it open its mouth? Why do you think it's doing that?

YOU WILL NEED: a live fish in water

Inspecting the gills of our fish

Inspecting the gills of our fish

Fish Anatomy and Dissection

8. Dissect fish & review main character traits of a fish. Refer to this fish dissection lesson plan and/or this fish dissection lesson plan to provide you with procedures and questions to ask as you dissect the fish.

YOU WILL NEED for each group of 3-5 children:

  • dead fish - I've dissected fish with groups of students at least half a dozen times. We're purchased whole fish at Asian markets and used perch caught from a local pond. Twice we've used preserved one, but I wouldn't recommend that. They are so tough and rubbery. Get fresh fish if you can.
  • disposable gloves
  • a sharp pairing knife and a hard, disposable plastic plate
  • disinfectant wipes & Lysol or other air freshener (optional)
A fish scale magnified so that you can see the layers of growth.  Year one's growth is in the middle and then the rings grow outward -- just like tree rings.  You can also tell the difference between summer growth and winter growth.

A fish scale magnified so that you can see the layers of growth. Year one's growth is in the middle and then the rings grow outward -- just like tree rings. You can also tell the difference between summer growth and winter growth.

Fish Scales

9. (Optional) As children finish washing their hands, let them look at fish scale under a microscope and count how old the fish is. Just like trees, fish scales grow a circle for each year a fish is alive. Honestly, we couldn't see any circles on the scales we looked at. I guess we needed a more powerful microscope or a larger fish. It was still neat to see the scale under the microscope anyway, though.

YOU WILL NEED: a microscope and microscope slide

Scales vs. Slime

10. Introduce herpetology: the study of reptiles and amphibians. It comes from the Greek word herpeton which refers to "creeping, crawling creatures that move about on their bellies." Amphibians & reptiles are called herps.

11. Scales vs. Slime: Let children touch a piece of clay with rows of shelled sunflower seeds stuck in it and a piece of plastic wrap sprayed with thin layer of non-stick cooking spray.

  • Have children describe how each feels.
  • Which do you they think represents the reptile skin? The amphibian skin?
  • Do let them know this is a generalization because some toads have dry, rough skin & some geckos have smooth skin with inconspicuous scales.

YOU WILL NEED:

  • a small plate with a piece of clay with rows of shelled sunflower seeds stuck in it
  • a small plate with a piece of plastic wrap sprayed with thin layer of non-stick cooking spray

Amphibian vs. Reptile Eggs

12. Let children touch some tapioca that's been sprinkled in a small bowl filled with boiling water and touch a few grapes and/or ping pong balls laid on sand or dirt in a bowl.

  • Have the children describe some of the differences between them.
  • Which do you think represents reptile eggs? Amphibian eggs?
  • Amphibian eggs don't have shells, so they do not have much protection from drying out.
  • Reptile eggs stay moist because they are laid in water or near moist areas on land. They're firm but not brittle (like bird eggs). Reptile eggs can vary. Turtle eggs are round with a smooth shell. Snake eggs are