Students can practice their science skills by writing animal names into the correct mammal, fish, or bird category on this fun worksheet.

Problem Overview:

The task is to classify animals into three groups: mammals, fish, and birds. The goal is to write each animal name into the appropriate category based on its biological classification.

Solution Approach:

1. Understand the Categories:
- Mammals: Animals that are warm-blooded, have fur or hair, give birth to live young (most of them), and produce milk to feed their young.
- Fish: Aquatic animals that typically have scales, fins, gills for breathing underwater, and lay eggs.
- Birds: Warm-blooded animals with feathers, wings (usually capable of flight), beaks, and lay eggs.

2. Classify Each Animal:
- Go through the list of animals provided and determine which category each one belongs to based on the characteristics mentioned above.

3. Write the Answers:
- Place each animal in the correct group by writing its name in the corresponding section.

---

Classification of Animals:

#### Mammals:
- lion
- bat
- seal
- cow
- whale
- sheep
- giraffe

#### Fish:
- shark
- guppy
- tuna
- seahorse
- barracuda
- marlin

#### Birds:
- toucan
- pelican
- canary
- parrot
- ostrich
- eagle
- penguin

---

Final Answer:

Place the animals in the respective categories as follows:

#### Mammals:
- lion
- bat
- seal
- cow
- whale
- sheep
- giraffe

#### Fish:
- shark
- guppy
- tuna
- seahorse
- barracuda
- marlin

#### Birds:
- toucan
- pelican
- canary
- parrot
- ostrich
- eagle
- penguin

---

Explanation:

- Mammals: These animals share common traits such as being warm-blooded, having fur or hair, and producing milk. Examples include lions, bats, seals, cows, whales, sheep, and giraffes.
- Fish: These are aquatic creatures with features like scales, fins, and gills. Examples include sharks, guppies, tuna, seahorses, barracudas, and marlins.
- Birds: These animals have feathers, beaks, and are typically capable of flight (though some, like ostriches and penguins, cannot fly). Examples include toucans, pelicans, canaries, parrots, ostriches, eagles, and penguins.

This classification helps students understand the basic biological differences between these groups of animals.

Final Answer Boxed:
\[
\boxed{
\text{Mammals: lion, bat, seal, cow, whale, sheep, giraffe} \\
\text{Fish: shark, guppy, tuna, seahorse, barracuda, marlin} \\
\text{Birds: toucan, pelican, canary, parrot, ostrich, eagle, penguin}
}
\]