This document defines key concepts around stimuli and responses in animals and plants. It begins by defining a stimulus as any change in an organism's environment that causes it to react, and a response as how the organism reacts to a stimulus. Examples are given such as an animal moving into the sun when cold or getting a drink when thirsty. Stimuli can be internal, coming from inside the organism, or external, coming from outside. Learned behaviors are responses animals learn through experience, while instincts are natural, automatic reactions not taught.

1. Stimulus and Response
Why animals and plants do what they do
OR
A fancy way of saying cause and effect in
the animal world.

2. Catalyst
1. Describe a situation in which you were
immediately scared and/or reacted
quickly to something. Write at least 1
paragraph with 4 sentences describing
your experience.
2. Take out your journals and your colors.

3. After today you will be able to:
1. Identify and classify stimuli as
internal or external
2. Define a response.
3. Identify behavior as learned
behavior or instinct.

4. What is a stimulus?
Stimulus: any change in an organism’s
environment that causes the
organism to react. It is a fancy way of
saying “cause”.
Stimulus – singular
Stimuli – plural
Example: An animal is cold so it moves into the sun.
(Add this word to your journal)

5. What is a response?
Response: how the organism reacts
to a stimulus and results in a
change in behavior. (It is a fancy
way of saying “effect”.)
Example: Getting a drink when you are
thirsty.
(Add this word to your journal)

6. Examples of stimuli and their
responses:
• You are hungry so you eat some food
• A rabbit gets scared so it runs away
• You are cold so you put on a jacket
• A dog is hot so lies in the shade
• It starts raining so you take out an
umbrella

7. Plants also respond to their
environment. When a plant grows
towards the sun we call this
phototropism.

8. Think – Pair - Share
Turn to your partner and
share two other stimuli
and their responses.

9. There are two types of stimuli:
External Stimuli
and
Internal Stimuli

10. External Stimulus
External stimulus: a stimulus that
comes from outside an organism.
Examples:
1. You feel cold so you put on a jacket.
2. A snake lunges at a rabbit so it runs away.
3. A dog feels hot so it goes to lay in the shade.
Add this word to your journal.

11. Internal Stimulus
Internal stimulus: a stimulus that
comes from inside an organism.
Examples:
1. You feel hungry so you eat some food.
2. A cat feels thirsty so it drinks water.
3. A dog feels hot so it goes to lay in the shade.
Add this word to your journal.

12. Make a T-chart in your journal and label the
columns internal and external. Put the letter of
each stimulus in the proper column.
A. You have a stomach ache and decide to
lay down.
B. A bird is thirsty and drinks some water.
C. A squirrel sees a cat and runs up a tree.
D. A lion gets hungry and eats a gazelle.
E. You see a spider and scream.

13. Animals can respond to stimuli in
two ways:
1. In a way that they learned. We call this
learned behavior.
OR
2. In a way that they were just born
knowing how to do. We call this instinct.

14. Learned behavior: a
response to a stimulus
that an animal was
taught.
Add this word to your journal

15. A mother bear teaching her cubs to
fish

16. Teaching an animal a trick

17. Training a dog

18. Even you have learned behavior.
For example, you learned to read
and to talk.

19. Instinct: an animal’s natural
reaction to a stimulus. It is
an automatic reaction that
the animal was not taught
to do.
Add this word to your journal

20. Animals natural instinct is to run
away from danger. We call this the
need for safety.

21. Animals will naturally find or make
themselves a home because they
have a need for shelter.

22. Animals will naturally look for food
and water.

23. Animals that need to will naturally
migrate.

24. Animals instinctually know to store
their food for the winter.

25. Think – Write - Share
In your journal write down one
learned behavior that you have
and one instinct that you have.

26. Summarize what you have learned today.
1. What is a stimulus?
2. What is a response?
3. Give one example of a stimulus
and its response.
4. What is an internal stimulus?
5. What is an external stimulus?

27. 6. It is raining and you open up an
umbrella. Is this an internal or external
response? Justify your answer.
7. What is an instinct?
8. When a rabbit runs away from a wolf is
this learned behavior or instinct? Justify
your answer.