Frank Drake first tried out this equation at a 1961 meeting of SETI, which obviously stands for the Search for Extraterrestrial Intelligence. Register to explore the whole course here: https://school.bighistoryproject.com/bhplive?WT.mc_id=Slideshare12202017

1. TEACHER MATERIALS
Page 1
ANYONE OUT THERE (THE DRAKE EQUATION)
BIG HISTORY PROJECT / LESSON 10.3 ACTIVITY
Purpose
This activity is going to get students thinking about the possibility of intelligent life beyond
Earth. Starting with the large numbers of stars in the Milky Way, students will take a
close look at the number of possible habitable worlds in our galaxy alone. Students will
use the most recent scientific evidence and discoveries to discuss, imagine, and come
up with their own ideas about how many of these worlds there might be in the galaxy.
Process
Divide students into six groups and assign each group a number. Direct the group to
focus on the question on the Anyone Out There? Worksheet that corresponds with their
group number. Tell the groups that they will have two minutes to discuss their group’s
question. Reassure students that there are no “right” answers to these questions; they
are to make educated guesses.
Now tell students that there are hundreds of billions of stars in the Milky Way. For this
activity, we are going to estimate that there are 400 billion stars in our galaxy. That’s
400 billion potential locations for life. Write the full number (400,000,000,000) on a
board or projector big enough so that all the students can see. Ask each group to read
their question and share their best guess and a brief rationale. As each group reports
their answer, track the resulting number of star systems capable of supporting life.
Below is an example of what you might write on the board; your students’ answers will
vary.
• Start
400,000,000,000
• Group 1 replies half of the stars might have planets orbiting them.
200,000,000,000
• Group 2 replies that one of every 100 planets might have an environment that
could support life.
2,000,000,000
• Group 3 replies that simple life will form on these planets one out of every 1,000
times.
2,000,000
• Group 4 replies that intelligent life will form on these planets one out of every
1,000 times.
2,000
• Group 5 replies that 1 in 100 civilizations will communicate over interstellar
distances.
20
• Group 6 replies that an intelligent civilization might survive 1 billion years. (To
reflect the odds that an intelligent civilization elsewhere in the galaxy overlaps
with our own, we multiply the number of possible star systems by the fraction of
time this civilization might survive. In this case, it would be 1/10th of the age of
our galaxy.
2
If you ended up with a one or a zero then students predicted that we are alone in the
galaxy. A number greater than one means that the group estimated that we could detect
another intelligent, communicating civilization close by. A number less than 10 implies
that they are far away, and that we won’t be able to detect them soon, as was the case
in the example above.
Tell students that currently, we only have the technology to detect stars with planets that
are a few light years away. Therefore, we’ve only explored a tiny fraction of our galaxy.
If we were ever to detect a signal from another intelligent civilization, we would have to
figure out what they are saying, how to respond, and then come up with a way to send
them a response. However, the biggest problem would be that it would take a very long
time to both receive and send the message.
At the end of the discussion, ask students if they have heard of SETI, the Search for
Extraterrestrial Intelligence. Tell students that they just calculated the likelihood of
other civilizations based on the Drake Equation. In 1961, astronomer and astrophysicist
Frank Drake took the six variables the groups just discussed and brought them to a
SETI meeting. His goal was to get scientists to think about the main things we need to
consider when thinking about the probability of communicating with other life.

2. Name: Group:
STUDENT MATERIALS
Page 1
ANYONE OUT THERE (THE DRAKE EQUATION)
BIG HISTORY PROJECT / LESSON 10.3 ACTIVITY
Purpose
This activity will get you to think about the possibility of intelligent life beyond Earth.
You’ll take a closer look at the number of possible habitable worlds in our galaxy by
using the most recent scientific evidence to estimate how many of these world might
support life.
Process
Your teacher will divide the class into six groups. Your group will have a number and that
number will tell you which of the questions below to focus upon.
It’s important to remember that scientists really don’t know the answers to any of
these questions! They are constantly collecting and analyzing new data, and refining
their estimates based on this information. The point of this activity is to consider the
possibilities, and to come up with an estimate with your group.
Spend two minutes discussing your group’s question and agree on an answer. Be ready
to share your answer when your teacher calls on your group.
Group 1
Out of all of the stars in the Milky Way, how many have at least one planet orbiting them?
(Choose one)
• All of them
• Half of them
• 1/4 of the stars
• 1 out of 10 stars
Group 2
How many planets in the Milky Way have the right environment to support life? (Choose
one)
• 1 out of every 10 planets have an environment that can support life
• 1 out of every 100 planets have an environment that can support life
• 1 out of every 1,000 planets have an environment that can support life
Group 3
On a planet that has the right environment to support life, how often does any form of
life ever develop? (Choose one)
On a planet with a hospitable environment,
• Simple life forms will develop every time
• Simple life forms will develop 1 out of 10 times
• Simple life forms will develop 1 out of 100 times
• Simple life forms will develop 1 out of 1,000 times
Group 4
Once a planet has simple life, how often does that ever develop into intelligent life?
(Choose one)
• Every time
• 1 in 10 times
• 1 in 100 times
• 1 in 1,000 times
Group 5
How many intelligent civilizations will ever communicate over interstellar distances?
(Choose one)
• All intelligent life will communicate
• 1 out of 10 civilizations will communicate
• 1 out of 100 civilizations will communicate
• 1 out of 1,000 civilizations will communicate
Group 6
How long will an intelligent, communicating civilization survive? (Choose one)
• 1 billion years (about 1/10th of the age of our galaxy)
• 100 million years (about 1/1,000th of the age of our galaxy)
• 1 million years (about 1/10,000th of the age of our galaxy)
• 10 thousand years (about 1 millionth of the age of our galaxy)