Acting is said to be the study of human behavior. So, in addition to their own memories and imaginations, actors must depend on their powers of observation.
As an actor, you must become aware of how other people feel, move, speak, think, and behave. You must be able to recall what you observe, and use it to build believable characters.
To test your powers of observation, look around the classroom and choose an object, such as a poster, and quietly observe it for one minute. Concentrate on the colors, shapes, printed words, and textures. Also pay attention to how the item makes you feel. Now close your eyes and try to re-create the object in your mind. Now, without looking at the object, write down every detail you remember. Compare what you have written to the object. Did you miss anything?
Suppose, for example, that you decide upon a treasured toy from your early childhood. Using your powers of observation, you will recall or re-create this item in such a way that your audience will visualize the object you describe. But also you have to be able to share what see with others.