Animal Life Cycles


In this lesson, students will be able to define a life cycle, identify common steps of a life cycle, and explain and compare different life cycles. The lesson is an overview of animal life cycles that apply to animals such as insects, amphibians, birds, reptiles, fish, and even humans.

The lesson focuses on metamorphosis, egg-laying, and live births. The students will compare the different life cycles, stages involved, and other characteristics of each. You can use this lesson in conjunction with other lessons related to the various aspects of an animal’s life.

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What our Animal Life Cycles lesson plan includes

Lesson Objectives and Overview: Animal Life Cycles introduces students to the process by which various animals grow. Students will discover that some steps among various life cycles are similar. They will also learn about the stages that are unique to a specific animal or life cycle. This lesson is for students in 3rd grade, 4th grade, and 5th grade.

Classroom Procedure

Every lesson plan provides you with a classroom procedure page that outlines a step-by-step guide to follow. You do not have to follow the guide exactly. The guide helps you organize the lesson and details when to hand out worksheets. It also lists information in the yellow box that you might find useful. You will find the lesson objectives, state standards, and number of class sessions the lesson should take to complete in this area. In addition, it describes the supplies you will need as well as what and how you need to prepare beforehand. For this lesson, you will need construction paper. Students will also need internet access for a portion of the lesson.

Options for Lesson

You will find several suggestions for additional ideas and activities in the “Options for Lesson” section of the classroom procedure page. One thing you can do is have students work in pairs or groups for the activity rather than alone. As another activity, students in small groups could create more in-depth reports on a specific animal and its life cycle. They could include one large picture of the animal and present the report to the class. Another option is to have students create one or more poems for each of the life cycles, explaining the different steps and including other pertinent information for the readers. One more idea is for students to research the timeline of various animals from egg to birth. They could create a graph that displays the differences and analyze the information, comparing it to life expectancy data.

Teacher Notes

The teacher notes page provides an extra paragraph of information to help guide the lesson and remind you what to focus on. The blank lines on this page are available for you to write out thoughts and ideas you have as you prepare the lesson.


Animal Life Cycles

The Animal Life Cycles lesson plan includes a total of six content pages. All animals experience birth, life, sometimes reproduction, and death. In fact, this is the simple life cycle of all living things, not just animals. An animal’s life cycle leads to the reproduction of new animals, and the process is continuous. As some animals die, others are born.

In most cases, the rate at which animals reproduce is faster than their rate of death. About 360,000 new babies, for instance, are born every day, but only about half that number of humans die each day. Therefore, for every human that dies, two new humans are born. The birth and death rates for other species vary.

All animals are part of a life cycle. They are born, become adults, reproduce, and die. However, those simple stages may vary depending on the species. Some animals hatch from eggs, are born from the mother, or undergo special changes during their life cycle. In fact, the ways animals change is part of their life cycle.

These changes are different for different animals. Some animals look like the parents when they are born. Others do not look like their parents. Some change color or shape, and some grow new structures. The life cycles of different animals might include metamorphosis, egg laying, or live births. The lesson describes each of these three types of life cycles.

Metamorphosis Life Cycle

There are roughly 900,000 different kinds of living insects, and they represent about 80% of the world’s species. They are the most diverse group of organisms in the world. Around 90% of all insects go through a life cycle called complete metamorphosis. This is the process by which an organism changes from an immature form to an adult form in more than two stages. The other 10% of insects experience incomplete metamorphosis that involves only three total stages.

During complete metamorphosis, nearly all insects go through four stages. The lesson uses the butterfly as an example to illustrate this point. The first stage is egg. This is the unborn stage that involves a female laying an egg. The next is larva, which is the young stage. Feeding takes place during this stage, leading to the pupa stage. The pupa is an inactive stage during which the organism is growing and camouflaged. Finally, the adult stage involves breeding, and some insects will grow wings.

During incomplete metamorphosis, there are just three stages. One of those is the nymph stage, which is the second of the three. Most of the feeding takes place during this stage. Dragonflies, grasshoppers, and cockroaches develop during incomplete metamorphosis.

Some amphibians also go through metamorphosis. The lesson uses the example of a frog. The first stage, like with insects, is the egg stage stage during which the male fertilizes the eggs in jelly-like fluid. Tadpole is the next stage. First, tadpoles develop inside the egg. The outer part breaks open so the tadpole can swim out. Next, they become a froglet, which is when the body begins to change and prepares for life outside the water. Finally, the adult frog loses its tail and can live out of water.

Egg-laying Life Cycle

The next type of life cycle is egg-laying. Many animals, including fish, reptiles, and birds, lay eggs. The young hatch and begin to simply grow larger without many changes. These animals don’t necessarily change color, and they don’t lose or gain body parts as the animals do during metamorphosis. There are three simple steps in the egg-laying life cycle, which the lesson outlines using the chicken as an example.

A hen at 6 months old produces an egg inside its body, which a rooster can fertilize. Next, the hen lays the fertilized eggs inside of which are tiny embryos that grow for about 21 days. Finally, a chick hatches from the egg and can feed itself within just a few hours. Over time, it grows into a hen or rooster. Six months later, the cycle begins again.

The size of an egg will vary depending on the animal species. Ostrich eggs are the largest in the world, but other eggs are very small. Some eggs don’t survive once they are produced because they are food for other animals. This is especially true of fish eggs.

Speaking of fish, students will learn that the life cycle of a fish includes four stages. First, a fish lays thousands of eggs. Second, the eggs become larvae at which point the organism spends large amounts of time growing (or getting eaten by predators). Survivors of this stage become juvenile fish, sometimes called a fry, and continue to grow. Finally, the fourth stage is when they become adult fish that lay eggs of their own.

Live Birth Life Cycle

The third animal life cycle involves live births. Nearly all mammals go through a live birth life cycle, including humans, dogs, bears, horses, and many others. These animals don’t lay eggs, lose or grow new body parts, or change much in appearance as the young grow into adulthood. Of course, the growth itself produces changes, but the change is mostly that the young get larger over time.

A live birth is the simplest of the life cycles. The young will grow slowly into an adult and inherit certain traits from the mother and father. This life cycle involves four stages—before birth, baby, child or adolescent, and adult. During the before birth stage in humans, an egg is produced inside the female animal and fertilized by the sperm of a male. The resulting embryo grows for about nine months.

The baby stage is when the offspring is born. Unlike the animals that undergo metamorphosis or egg-laying, the young must depend on the parent for care. One interesting fact is that in humans, babies have more bones than adults that eventually fuse together as they grow.

Depending on the species, the child and adolescent stage involves continued growth. Humans go through body changes such as puberty. Most mammals don’t distinguish between child and adolescent stages. For many, the young begin to care for themselves much sooner and body changes occur earlier than in humans. The last stage is adulthood during which the cycle can begin again.


The Animal Life Cycles lesson plan includes three worksheets: an activity worksheet, a practice worksheet, and a homework assignment. Each one will reinforce students’ comprehension of lesson material in different ways and help them demonstrate when they learned. Use the guidelines on the classroom procedure page to determine when to distribute each worksheet to the class.


For the activity, students will create stories that relate to an animal’s life cycle. First, they will imagine themselves as one of the types of animals they learned about in the lesson (except human). They will write the story from the first-person perspective about the animal’s life cycle experience. In each story, students will begin as eggs and ensure they mention each subsequent stage. Throughout the story, they will include pictures they draw (or find online or elsewhere) and research more information that would be useful to the stories. The lesson provides an example to help guide students in the assignment. When they finish, you can grade them using the rubric at the bottom of the worksheet.


The practice worksheet is split into multiple sections. The first section displays the stages of five different life cycles. Students must order the stages beginning with egg as 1. (All the life cycles start with egg.) In the next section, students will match definitions and terms. There is a word bank for them to use to the right of the descriptions. In total, they must correctly match eight definitions and terms. Finally, the last section requires students to decide whether each of seven statements is true (T) or false (F).


For the homework assignment, students will match the stages of four different animal life cycles to the correct descriptions. The cycles include butterfly, fish, frog, and human. Students will use the word banks specific to each group of descriptions. In total, there are 17 descriptions and stages to match.

Worksheet Answer Keys

There are answer keys for the practice and homework worksheets of this lesson plan. Students’ responses for the practice worksheet should closely resemble those of the answer key. There will be some variation given the nature of the assignment. The answer key for the homework assignment provides images of two sample dioramas. You may want to show them to your students to give them an idea of what they can do. If you choose to administer the lesson pages to your students via PDF, you will need to save a new file that omits these pages. Otherwise, you can simply print out the applicable pages and keep these as reference for yourself when grading assignments.

Additional information


3rd Grade, 4th Grade, 5th Grade



State Educational Standards


Lessons are aligned to meet the education objectives and goals of most states. For more information on your state objectives, contact your local Board of Education or Department of Education in your state.

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Life cycles

The students were motivated to research other life cycles after this activity. It was a great intro lesson.

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Good resources

Good resource easy but challenges kids to think and read.