er and programming-based activities.
More formal studies are needed that
validate that CS Unplugged is effective in meeting its goals.
Another key to the widespread use
of CS Unplugged is its ability to get
kids engaged in the activities physically, and most activities encourage
group work so kids work together to
solve problems, much like computer
scientists do when working on large
complex software and hardware systems. CS Unplugged exemplifies an
educational theory known as experiential learning, where participants learn
through activity outside of a standard
academic setting. 5 By being physically
part of the solution to a problem as it
is being solved, kids learn from observations and experiences. Unlike some
introductory programming activities
that tend to promote solo activity,
the CS Unplugged activities put kids
physically in the middle of the problem, getting them moving, working together, sharing ideas, and designing
solutions.
One activity in CS Unplugged involves compressing text by finding repeated letter sequences. Kids can work
together to compress some large paragraphs to a fraction of their size, competing to see who can compress the
text the most. As a result of this activity, kids learn one way their computer
makes files smaller so they can store
more on their hard drive. It is one thing
for them to click the Compress option
for a file. It is another thing to gain
an appreciation for how that process
works. And some kids wonder if there
are other compression algorithms and
why this one works so well, leading to
further exploration.
Another activity simulates parallel
sorting, where children walk through
a parallel sorting network drawn on
the ground with chalk, comparing
themselves using some measure with
other children they encounter, following the appropriate path to another
node in the network until they reach
the end. They see that no matter how
they are organized initially, the network will lead them into sorted order.
The activity comes with several networks the teacher can use, and it can
be adapted based on the number of
students in the activity.
Yet another activity involves a set of
The teacher, or someone who is in
on the “trick,” can then claim to make
the problem even more difficult by
adding an eighth row and eighth column with seemingly random choices:
X O X X X X O X
X X X X X O X O
O X O O O X O O
X O X X O X O O
O X O O X O O O
O O X O X O X X
X O O O X X X O
O X O X X O X O
The teacher can then leave the
room, and a child can change one of
the magnets to the other magnet. For
example, the child changes the magnet
in the second row and third column
from X to O:
X O X X X X O X
X X O X X O X O
O X O O O X O O
X O X X O X O O
O X O O X O O O
O O X O X O X X
X O O O X X X O
O X O X X O X O
The teacher returns and magically
picks out the magnet that changed,
astounding the children. The teacher
asks how this is possible, giving children a chance to discuss solutions
with each other, expressing various algorithms or techniques that may have
been used. Often, students will eventually see the teacher did not put in
a random eighth row and eighth column. Instead, the extra row and column set the number of each magnet
in each row and column to be even.
The change creates exactly one row
and one column with an odd number
of each magnet, leading to the magnet
that was changed.
The computational thinking principle illustrated in this activity is that
of parity, detecting errors in data,
which computers have to do constantly. The CS Unplugged activity
write-up gives teachers information
about parity that they can present to
children along with extension activities. For example, what happens if two
magnets changed? Can we detect that
the change occurred? Can we identify
which magnets changed?
One of the keys to the success of CS
Unplugged and its use worldwide is
the fact the activities do not require a
computer at all. Some schools do not
have a computer lab for students to
write code. If they do have computer
labs, they are often used for word pro-
cessing and Web surfing for research
for other courses. CS Unplugged ac-
tivities can be done entirely without
computers. When the CS4HS (Com-
puter Science for High Schools) work-
shop was launched at Carnegie Mel-
lon University in 2006, participating
high school teachers said they could
not teach computer science because
they did not have any computers, or
enough computers, in their schools.
The workshop started with CS Un-
plugged, and all of the teachers sub-
sequently reported using these activi-
ties successfully in their schools the
following year with an increase in stu-
dent interest in computing.
Activities in CS Unplugged support
the principle of computational thinking, 5 which promotes the idea that
problem-solving skills and computational techniques used in computer
science should be a part of every person’s education and are applicable to
a wide variety of fields, not just computer science. Although one study
suggests CS Unplugged activities do
not inspire young people to pursue
computer science in college, 4 the
primary goal of these activities is to
expose students to computing as an
intellectual discipline that goes beyond their understanding of computers as a tool and a toy. Additionally,
these unplugged activities are meant
to be supplementary, used for short
periods to get kids working together,
and to give teachers and students a
chance to step away from the comput-
It is one thing for
students to click
the Compress option
for a file. It is another
thing to gain an
appreciation for how
that process works.
