IDENTIFICACIÓN DE LA IDEA PRINCIPAL

What is a Main Idea?
The main idea of a passage is the core of the material, the particular point the author is trying to convey. The main idea of a passage can be stated in one sen­tence that condenses specific ideas or details in the passage into a general, all inclusive statement of the author's message. In classroom discussions, all of the following words are sometimes used to help students understand the meaning of the main idea:
thesis
main point
central focus
gist
controlling idea
central thought

Recognize General and Specific Words
The first step in determining the main idea of a selection is to look at the specific ideas presented in the sentences and try to decide on a general topic or subject under which you can group these ideas. Before tackling sentences, begin with words. Pretend that the sentence ideas in a selection have been reduced to a short list of keywords. Pretend also that within the list is a general term that expresses an overall subject for the keywords. The general term encompasses or categorizes the key ideas and is considered the topic of the list.

Exercise 1
Circle the general term or subject for each of the following related groups of ideas.
a) satin/wool/fabric/silk
b) chimpanzees/orangutans/apes/gorillas
c) cirrus/clouds/cumulus/stratus
d) oats/wheat/corn/grain
e) Alps/Appalachians/mountains/Rockies
f) shrimp/crustacean/crab/lobster

Exercise 2
Circle the phrase that could be the topic for each list.

a) totaling yearly income
substracting for dependents
filing an income tax return
mailing a 1040 form

b) paying fees
buying books
starting college
going to class

c) picking up seashells
vacationing at the beach
walking in the surf
riding the waves

d) pushing papers under sticks
piling the logs
building a fire
striking a match

Exercise 3
Circle the phrase that best describes the topic or subject for each group of sentences.

Group 1
1. To provide a favorable climate for growing grapes, the winter temperature should not go below 15° F, and the summers should be long.
2. During the growing season, rainfall should be light.
3. A gentle movement of air is required to dry the vines after rains, dispel fog, and protect the vines from fungus disease.

Protecting Grapes from Disease
Appropriate Temperatures for Growing Grapes Appropriate Climates for Growing Grapes

Group 2
1. For example, faced with fewer expansion opportunities within the United States, Wal-Mart opened new stores abroad and foreign sales reached $7.5 billion in three years.
2. As more and more companies engage in international business, the world is becoming a single, interdependent global economy.
3. In a plan to become a transglobal giant, Chrysler, one of America's apple pie auto companies, merged with Germany's Daimler-Benz to become DaimlerChrysler.

International Auto Mergers
A Global Economy
Wal-Mart Expansion

Group 3
1. After accidents, suicide is the second leading cause of death among adoles­cents.
2. In a national survey, 42 percent of the 8th through 10th grade girls reported contemplating suicide sometime in their lives.
3. In the last forty years, the suicide rate among young men 15 to 19 years of age has quadrupled.

Prevention of Suicides
Increase in Adolescent Suicides
Reasons for Teen Suicides

Group 4
1. Some scientists believe that the vestigial diving response offers proof that humans evolved from aquatic animals.
2. If you submerge your face in water, your pulse rate is likely to drop and your metabolic rate decreases.
3. This slowdown suggests a vestigial diving response that would allow humans to remain submerged longer.

Human Science
Vestigial Linkage to Aquatics
Lowering the Metabolic Rate

Group 5
1. Simply drinking water is the best way to prevent dehydration from sweating.
2. Taking salt tablets before drinking water can dehydrate the body even more by extracting water from body tissue.
3. Plain water is better than beverages containing sugar or electrolytes because it is absorbed faster.

Salt Tablets versus Water
Value in Plain Water
Preventing Dehydration


Exercise 4
Read the following groups of three sentences and then write a phrase that best states the subject or general topic for the sentences.

Group 1
1. The albatross is one of the few birds that is designed to live at sea and it seldom visits land.
2. Because it has special glands that excrete salt, it can drink seawater and eat salty fish.
3. The albatross's unusually long wings provide the lift for it to glide almost endlessly in high winds over rough seas.
General topic? _______________________________________________

Group 2
1. Once children begin to speak and understand words, their progress is remarkably fast.
2. Most children begin speaking at 1 year of age and speak only 2 to 3 words.
3. By age 2, they speak about 50 words and understand 200 to 300 words.
General topic? _______________________________________________

Group 3
1. Dr. Sylvia Castillo of Stanford University founded the National Network of Hispanic Women.
2. This organization publishes a national newsletter that focuses on the successes of Hispanic women in academia and business.
3. The organization has become an important voice for Hispanic issues relating to gender.
General topic? ________________________________________________

[tomado del libro Breaking Through.College Reading de Brenda D. Smith, Longman Publishers]