Children learn that living things grow and change. They learn to compare animal parents and babies. They see that some animal babies do not look like their parents. From tadpole to frog, egg to chicken, caterpillar to butterfly, and puppy to dog; students are introduced to, and learn the stages of, the life cycles of animals.
From tadpole to frog, egg to chicken, caterpillar to butterfly, and puppy to dog, learn the stages of the life cycles of animals.
- Students will understand that there are four different stages in an animal's lifecycle: First, it is born; second, it grows and changes and becomes an adult; third, it produces offspring; and fourth, it dies. The animal's offspring can have their own offspring, and so on. The "cycle" part of the word "lifecycle" means that although an individual animal dies, its characteristics can be carried on from generation to generation through reproduction.
- Students will know the details of the lifecycles of some of the different groups of animals.
- Mammals: Mammals are a class of animals that are born alive, have fur, and feed their young with milk. In addition, baby mammals require more care from their parents than other animals. Mammals include people and dogs. Lifecycle of a mammal (Dog example): First, the puppy is born alive; it is a smaller version of the parent. Then, the puppy grows and changes until it becomes an adult dog. When it is an adult, the dog can reproduce.
- Amphibians: Amphibians begin their lives in the water, but they live on land as adults. In addition, they hatch from eggs. Examples of amphibians include frogs and newts. Lifecycle of an amphibian (Frog example): Frogs lay their soft-shelled eggs in a pond to keep them from drying out. Then, the eggs hatch into tadpoles. Tadpoles are baby frogs, but they do not look like adult frogs. They have a tail and no legs, they swim like fish, they breathe with gills, and they eat plants. As a tadpole grows, it changes; it loses its tail and gills, it grows legs and lungs, and it eats bugs instead of plants. Soon, it looks like a small frog. When it becomes an adult, it can lay eggs that will hatch into new tadpoles.
- Birds: Birds have wings and feathers; in addition, they hatch from hard-shelled eggs. Birds include chickens and eagles. Bird lifecycle (Chicken example): Chickens lay their eggs in a nest; bird eggs have hard shells to prevent them from drying out, so they do not need to be laid in water. Each egg contains one chick. After it develops (about 21 days), the chick hatches from the egg. Soon after, the chick begins to look for food. As the chick gets bigger, it develops adult feathers and looks more like its parents. When the chicken reaches adulthood, it can lay its own eggs, which will hatch into baby chicks.
- Reptiles: Reptiles have dry, scaly skin, and most of them hatch from eggs. Examples include turtles and lizards. Reptile lifecycle (Turtle example): Female turtles lay their tough shelled eggs in holes that they dig on land; usually, they leave the eggs and never come back. When a baby turtle hatches, it looks like its parents. The baby turtle grows very quickly and becomes an adult. An adult turtle can lay its own eggs.
- Fish: Fish live their entire lives in the water. They breathe with gills, swim with fins, and protect themselves with scales. A fish begins as an egg that is laid in the water. When the fish hatches, it looks like a smaller version of the parent; it swims, has fins and a tail, and breathes with gills. The larva, or fry, will eventually grow into an adult that is capable of laying its own eggs.
- Insects: Insects have six jointed legs, three main body parts (head, thorax, and abdomen), and a protective exoskeleton. Insects include grasshoppers and butterflies. Metamorphosis is an important part of an insect's lifecycle, because it helps the insect to grow and change. Insects exhibit either simple metamorphosis or complete metamorphosis. The milkweed bug goes through simple metamorphosis, which has three stages (egg, nymph, and adult): It starts out as an egg. Then, the egg hatches and releases a nymph, which is a smaller version of the parent. The nymph molts and gets larger several times until it grows wings and becomes an adult. A butterfly goes through a complex metamorphosis, which has four stages (egg, larva, pupa, and adult): The butterfly starts out as an egg; then a caterpillar (a type of larva) hatches from the egg. The larva eats many leaves and grows quickly. Then it covers itself with a protective case and becomes a pupa; the pupa changes inside the case. Finally, an adult butterfly, which can produce its own eggs, emerges from the case.
- Students will realize that every baby animal will grow up and look similar to its parents. A puppy will grow up to be a dog, not a cat. However, individual animals may vary a little in their appearance. For example, dogs from the same litter may have different colorations and sizes.
- Pantomime: After watching the video, divide the students into two groups. One group represents the simple metamorphosis; the other represents complete metamorphosis. Have each group work out a way to show the other group what happens in their version of the lifecycle through pantomime. This activity can be done in pairs or small groups as well.
- Venn diagram: Choose two groups of animals that are highlighted in the video and produce a Venn diagram in front of the class that compares and contrasts their lifecycles. The students should come up with the information to fill out the diagram. Frog and chicken example:
- Differences: Frogs live in water as tadpoles and on land as adults; however, chickens live on land throughout their lives. Frogs have soft-shelled eggs that must be laid in the water; however, chickens have hard-shelled eggs that are laid on the land.
- Similarities: Frogs and chickens have the same general lifecycle (birth, growth, reproduction, and death). Frogs and chickens both hatch from eggs.