activities help students to understand the difference between science
and pseudoscience by investigating some of astrology's claims. Letting
students have a good discussion can be very effective. We encourage
you to read "Your Astrology Defense Kit" before doing these activities.
test the validity of astrology with three activities:
Charting birthdates of U.S. presidents
Comparing horoscopes in different newspapers
Attempting to identify their own horoscope from an
unidentified list of daily predictions
activity was written by Andrew Fraknoi (Foothill College and Astronomical
Society of the Pacific) and incorporates suggestions by Diane Almgren,
Daniel Helm and Dennis Schatz.
Copyright © 1995, Astronomical Society of the Pacific, 390
Ashton Ave., San Francisco, CA 94112. This activity may be reproduced
for nonprofit purposes.
Activity 1: Testing Astrology with the
Birthdays of the Presidents
will tell you that the Sun sign (which is the sign of the zodiac
the Sun was in when a individual was born) is a crucial factor for
the occupation a person chooses and a strong determinant of overall
personality as it relates to one's job. As an example of how we
can test such a hypothesis, students can examine the birthdates
of the 41 men who have successfully run for the job of President
of the United States.
all, it takes a certain kind of personality to be President (outgoing,
well-spoken, ambitious). If personality and occupation are strongly
affected by Sun sign, we should find that the birthdays of the Presidents
are clustered in one (or a few) signs. If Sun signs do not affect
personality and occupation, the Presidents' birthdays should be
randomly distributed among the zodiac signs.
will fill out a worksheet to
determine the astrological signs of the 41 Presidents and discuss
their results. You will need to review the concept of random distribution
before doing this activity.
many Presidents do students expect to find under each sign if the
birthdays of the 41 Presidents are randomly distributed among the
12 signs of the zodiac?
there are 41 people, chance would classify 3.4 people (41 people
divided among 12 signs = 3.4 people per sign) into each of 12 random
"bins." With only 41 data points, you might expect one or two fewer
or one or two more Presidents in a given sign.
students to discuss other ways to test this hypothesis. What occupations
are also personality-driven but have more than 41 people in them?
(As discussed in Your Astrology Defense Kit, one group of
statisticians tested all the men who re-enlisted in the Marine Corps
- definitely a personality related career choice!)
2: Horoscopes from Different Astrologers
this activity, students compare horoscopes in different newspapers
from the same day. Ask students to bring in newspapers or buy them
yourself. You can also copy newspapers from a local library, although
using photocopies reduces the psychological impact of the activity
somewhat. The more newspapers you have, the better the activity.
the horoscope sections out of the papers and distribute them to
students. If possible, cut out the horoscopes in full view of the
students for greater impact. Ask several students to read aloud
the different horoscopes of one or more selected students from the
various newspapers. Discuss the following questions:
How well do the predictions of different astrologer agree for that
How specific are the newspaper statements?
In what ways could the statements apply to different people?
the students discuss some reasons why the predictions in astrology
columns might be so general and vague. If there is time, continue
the discussion by bringing up some of the "embarrassing questions
about astrology" in Your Astrology Defense Kit.
3: Mixed-up Horoscopes
this activity, students try to find their own sign from a variety
of unidentified signs in a horoscope column. Use an astrology column
from a recent newspaper (today, yesterday, or last weekend). It
is best to use an out-of-town newspaper so students are not likely
to have seen it. Cut out the horoscopes and remove the dates, signs
and any telltale references to the sign, like "you're a real lion
at times." Be sure to make a copy of the full column for yourself
and put it aside. Mix up the order of the descriptions, and give
each one a number from 1 to 12. Transfer these numbers to your copy
for future reference.
each student write down his or her name and birthday on a piece
of paper. Distribute the sheet with all the numbered (but otherwise
unlabeled) horoscopes to the students and have them select the one
description that best fits the day in question. (Be sure you remind
them of the day the horoscopes apply.)
the students to predict how they think this experiment will turn
out. To prevent sudden changes of answers, ask students to exchange
papers at this point. Then put the signs and birthdates associated
with each numbered paragraph on the board. Have the class count
how many students picked their own sign among the 12 and how many
Sun sign astrology predicts one's day pretty well and everyone remembers
the day in question clearly (the astrologer's hypothesis), students
should in general be able to find their own paragraph. But if chance
instead of the stars governs the composition of those descriptions
(the skeptic's hypothesis), we would expect that only one out of
12 of the students would have selected the description for their
With small numbers of students in one class, it often happens by
chance that there are a few more correct picks than one would expect
by chance. With older students, this can give you a chance to discuss
the need for large samples in good statistical studies. If students
get intrigued by such extra hits, one way to check is to extend
the test to other students or school staff.