Both LS 1a and LPS A are offered in the fall and are introductory courses in biology and chemistry.  LS 1a integrates chemical and biological principles throughout the semester, and also applies these concepts to larger biological problems such as HIV and cancer.  LPS A is aimed at students who, based on their background in chemistry or biology, require additional preparation before taking further science courses at Harvard.  In LPS A, the first half of the semester is devoted to a study of general chemistry, and the second half of the semester explores molecular and cellular biology.  It is beneficial to already have some familiarity with basic chemical principles when taking LS 1a.  LPS A is particularly important for students with little or no chemistry background who plan to take PS 1 or PS 11 in the spring.

The biology and chemistry placements tests have been carefully constructed to give good advice about which course is most appropriate for you based on what you have learned in high school.  You should take the course that is most appropriate for your background.  Although LS 1a and LPS A take different approaches to studying chemistry and biology, either class will prepare you for later science classes.