These are general outlines. GMAT passages may include some, but not all of the lettered
paragraphs. The order of the ideas presented might also vary.

1) Chronological
a. Intro (why the history is important)
b. What happened from time A to time B
c. What happened from time B to C
d. What happened from time C to D

2) New Theory
a. Intro
b. What we used to think (old theories)
c. The new theory explained
d. Why new theory is important

3) Competing Theories
a. Intro
b. Theory A
c. Theory B
d. Author’s opinion about which is best

4) Examples Supporting a main argument
a. Intro with thesis
b. Example 1
c. Example 2
d. Example 3

5) Practical Science
a. New Theory
b. Hideously detailed scientific data/processes intended to distract you
c. How the new theory is useful

6) Methods of Study
a. Group A studies a particular topic by doing X
b. Group B studies the same topic by doing Y
c. Author thinks both methods are flawed.

7) Literature Critique
a. Presentation of a new book/study
b. Argument of the book outlined
c. Author of the passage gives his/her opinion on the validity of book/study

Source: GURU GUIDE