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Trout in the Classroom

The purpose of Trout in the Classroom is to raise awareness about Idaho’s aquatic resources by providing hands-on learning opportunities for Idaho students. Trout in the Classroom encourages students to actively participate in the learning process. By observing and caring for trout, students gain an understanding and appreciation of a trout’s life cycle and habitat requirements.

Trout Dissection

Originally aired May 19, 2020

We are with Jennifer Jackson of the Idaho Fish and Game for a trout dissection for the Trout in the Classroom curriculum.

Fish Fin Models

Week of April 27, 2020

This week (April 27-May 1) you will be making models to test how fins of different sizes and shapes help the fish to move through water. Review the Fish Fins Worksheet pdf and check your answers.

  1. You will be using a plastic bottle and plastic lids. I used a 2-liter pop bottle. Scientists use models to test ideas. When used in experiments data can be collected and used in scientific explanations about how things function and behave.Fin Model Example
  2. Place your bottle with the cap on it in a tub of water. Blow on the bottle or push it through the water to see how it moves. Take notes on how it moves through the water. Fin Model Example
  3. Look at the shape of your bottle and think about fish and the kinds of fins that they use to stabilize themselves in the water. The Fish and Fins worksheet can help you on this. Draw on a piece of paper two different shapes of anal fins to try on your bottle Use the plastic lids to cut out the anal fin models. Securely attach the first fin at the rear of the bottle. I used duct tape and it worked well. Again blow the bottle or push it through the water. Take notes on what happened. Did the bottle roll or turn or did it remain stable and continue straight ahead? Next, take that fin off and try the other fin. Secure it on the bottle with duct tape and test it in the tub. Which fin worked best? Why do you think that that fin model worked better than the other? Can you think of a fin arrangement that would be even more stable? Fin Model Example
  4. You can also modify your model by adding a caudal fin. Use the same procedure that you did with the anal fin. Draw your caudal fin on a piece of paper. Cut out your pattern and use it as a template on the plastic lid. Cut your caudal fin from the plastic lid. Secure it in the correct position on your bottle.
  5. This time you will need to have the bottle submerged to test it. Partially fill the bottle with water and replace the cap. The tail will need to be underwater when you float it in the tub. Again, push the model and watch it move through the water. Record your observations. How did adding the caudal fin change the model’s motion through the water?
  6. You can repeat the procedure again with pectoral fins. Record your findings.
  7. When you have completed your experiments, take a picture of your model. Share it with the rest of the class by sending the picture to We will share the pictures of the models on this page.
  8. Which aspects of your fin designs were effective? Did your models imitate the functions of real fish fins? What didn’t work? What could have worked better? What did you learn from this experiment in modeling? 

What fish share

Week of April 20th

There is an amazing variety of fish species living in many different habitats, from trout living in cold mountain streams to parrotfish living in tropical oceans. Even though there is great diversity among fish species, some general characteristics can be made about fish as a group.

Generally, fish have fins and a long, streamlined or narrow body that help them to swim easily through the water. The form, or shape, of a fish’s body and body parts, relates to their function, or how the parts work. Function also depends on form. This relationship exists in the natural world and also to things people invent and make.

A duck’s webbed feet help it to swim, and the streamlined shape of a submarine helps it move easily through the water. By observing and studying the different body parts of a fish, one can learn how the fish’s body functions, why the fish lives where it does, and how the fish is able

to get food. Making models is one way to learn about structures, their functions and how they behave under certain conditions. Models can be used to investigate how different types of fish fins help fish survive in their habitats. Making observations using models is one way to look at the world as a scientist.

Fish Fins

Fins are used to move, steer, stop and maintain position. Most fins are composed of fin rays covered by skin. The fin rays provide support and are necessary for fin movement. 

Trout have three unpaired fins: dorsal fin, anal fin and caudal fin. The dorsal and anal fins are essential in helping the fish stay upright. The caudal fin is the ‘tail’ of the fish and thrusts the fish through the water. It also acts as a rudder to steer the fish. 

Trout also have two paired fins: pectoral fins behind the gills and pelvic fins below and behind the pectoral fins. The pectoral fins act as brakes and help with side-to-side movement. The pelvic fins help with up and down movement.

Trout also possess an adipose fin which lacks fin rays. It is believed to help reduce drag and improve swimming efficiency.

For more information of fish fins check out this Fish Fin Presentation pdf.

Now that you know about the different fins, spend at least 10 minutes observing the fish swimming. Before you watch the video, write down what you think each fin will control.

Trout Underwater Relaxing Nature Background Video

Questions about fins?

  1. Observe how the fish move up, down, forward, backward, turn, stop and remain still.

  2. What happens when a fish moves its caudal fin?

  3. Pectoral fin?

  4. Dorsal and anal fins?

  5. Write a description of how the fins function to help the fish survive.

  6. Check the TIC page 70 to see if your ideas match with those of biologists.

Next week we will be making models of fish with fins using plastic bottles and plastic lids. Try to save some over the next week if you can. One liter water bottles, two litter pop bottles, and any round plastic bottle will work.

Dichotomous Key to Identify Fish

Week of April 6th

A dichotomous key is a tool that allows people to identify plants, animals, rocks and anything that you might want to identify in nature. Here you will be using a dichotomous key to identify fish. Using a series of questions that divide the fish into two groups, you will be able to find the correct name for the fish.

Try out the online activity to identify the different fish.

Online Fish Identification


If you are feeling good about using a key, here is a little harder one where you will identify aquatic critters. These include some of the critters that we studied last time as trout food. They are also important indicators of water quality in a fishing stream. After the first identification, you will need to print the image below to key out each of the critters.

Aquatic Critters Identification

What Do Trout Eat?

Trout eating a mosquito larva

Week of March 23rd

The cold, clean rivers and streams in Idaho attract fly-anglers from across the country who come to fish for trout in a pristine environment. Fly-anglers use artificial flies as bait. Artificial flies look similar to the trout’s natural diet of aquatic macroinvertebrate species.

Macro means large enough to see with the naked eye and invertebrate means they have no backbone. These animals live on rocks, logs, sediment, debris and aquatic plants during some period in their life. Macroinvertebrates include crustaceans such as crayfish, mollusks such as clams and snails, aquatic worms and the immature forms of aquatic insects such as stonefly and mayfly nymphs. Aquatic macroinvertebrates, such as insect larvae, are a large part of a trout’s diet. The flying adult forms of the aquatic insects are also food for trout.

Different species of macroinvertebrates have different characteristics, including body shape, exoskeleton color, feeding preferences and in-stream behaviors.

To make their fishing flies, anglers closely study the species they are imitating. They then wrap hooks with thread, yarn, feathers, and other materials of various colors to mimic the macroinvertebrate. To be successful, fly-anglers need to have knowledge of what fish eat and need knowledge of the food being eaten. Anglers need to know what the macroinvertebrates look like and their habits to trick a fish into biting their flies.

This information comes from Trout in the Classroom Curriculum Published by the Idaho Department of Fish and Game Funding provided by Wildlife and Sport Fish Restoration.

Meet the insects Trout like to eat


Toothed Dragon