Life Cycle of a Bird
Lesson 1
Most animals come from eggs. The eggs are
produced by the adult female. Many eggs contain everything needed
to form a new animal. Many eggs have a shell or outer covering.
The covering keeps the egg from drying out. It also protects the
new animal growing inside. Bird eggs have a hard shell. When the
animal has grown enough, it breaks out of the egg. This is called
hatching. Here you can see how a chicken hatches.
The new chick quickly grows into an adult. The
adult female can then lay eggs and the cycle continues.
Student Activity for Lesson 1
Obtain one hard-boiled egg and one uncooked
chicken egg. The hard-boiled egg should not have developed a
crack while cooking. Open the uncooked egg carefully (don't break
yolk) and place it in a petri dish.
Procedure:
A. Carefully crack the shell of a hard-boiled
egg. Peel the egg. Notice the dent at the end. Between this dent
and the shell was an air space.
- Use a hand lens to examine the shell and
its lining.
- Use a plastic knife to cut the hard-boiled
egg open and observe the inside of the egg. Notice the
white and yolk of the egg.
- Observe the uncooked egg in the petri
dish.
- Find the twisted strands of egg white.
- Find the white spot on the yolk. The white
spot is the part that may grow to be a chicken.
- Draw a picture of your findings and label
the parts of an egg.
Life Cycle of a Turtle
Lesson 2
Turtles, like most other reptiles, lay eggs.
The turtle eggs have a softer shell that feels like leather. When
the baby turtle has grown enough, it hatches. Newly hatched
turtles look very much like the adult. The young turtle quickly
grows into an adult. The adult female lays the eggs and the cycle
continues.
Life Cycle of a Frog
Lesson 3
Many young animals look much like their
parents. Others do not. In each stage of growth they become more
like their parents. Look at the pictures and notice how the frog
changes in each stage of growth.
The frog’s eggs are laid in water. The
eggs have a jellylike covering and look like a mass of jelly in
the water. Young frogs hatch from the eggs.A young frog, which
looks like a small fish, is called a tadpole. Like fish, tadpoles
have tails and breathe air from the water in which they live.
Gradually back and front legs form. The tail
disappears. Finally lungs form in the young frog. It can no
longer breathe in water. It must breathe in the air. The frog is
then an adult. The adult female can lay eggs and the life cycle
continues.
Life Cycle of a Grasshopper
Lesson 4
The grasshopper has three stages of growth. The
grasshopper, an insect, begins its life cycle in an egg. After
hatching, the young insect is called a nymph. A nymph is like a
tiny adult, but it does not have wings. The nymph becomes an
adult insect when it has wings and can fly. The adult female
grasshopper can lay eggs and the cycle begins again.
Life Cycle of a Butterfly
Lesson 5
Many insects, such as the butterfly, go through
four stages of growth. The egg is the first stage of growth.
Insect eggs may be laid almost anywhere. Often they are on leaves
or other food the insects can eat after they hatch.
After hatching, the young insect is called a
larva. A larva is the second stage of growth. A larva is always
hungry.
After a certain time, a larva stops eating.
Then it makes a covering for itself. The covering is usually
hard. Now the insect is called a pupa. A pupa is the third stage
of growth.
Inside the covering, the pupa slowly changes.
When the changes are complete, the adult insect comes out. This
is the fourth stage of growth. Now the insect looks the same as
other adults of its kind. The adult female can lay eggs and the
cycle begins again.
Life Cycle of a Fish
Lesson 6
Most fish grow in eggs outside the mother's
body. The parents usually do not protect the soft covered eggs.
Many eggs are produced so that enough young survive to continue
the species. When the eggs hatch the young look very much like
the adult. The adult is the final stage of growth. The adult
female can lay eggs to continue the life cycle.
Life Cycles of Mammals
Lesson 7
Most mammals do not hatch from eggs. The animal
grows in a special way in the female's body. Then they are born
live. When the young are born, the mother produces milk to feed
them. The babies need a lot of care. The young mammal then grows
to be an adult. The adult female can produce a young animal that
looks very much like itself. The animal's life cycle is then
complete.
Suggested Activity
Identify stages of
growth of various animals.
Procedure:
Draw and label the stages in the life cycle of
an assigned animal: (examples: grasshopper, butterfly, goldfinch,
frog, elephant). Cut into individual stages the completed drawing
of each animal's life cycle. Put all pictures in a bag. Have each
student take a picture out of the bag. Each student should then
find the other students who have drawings from the life cycle of
the same animals. The groups that form should reassemble the
order of the drawings to illustrate the life cycles of the
animals. The groups should share their completed life cycles.
