The bridge exercise shown below is a typical icebreaker for the first lesson of the course. It clears the fairway for the upcoming course ("breaks the ice") in several manners: It reduces social reservations by providing a problem that has to be solved together, it reduces the uncertainty for the course by giving a sense of achievement when the first problem of the course is solved and it introduces first terms and concepts of the course that can be experienced by practical work. The main stakeholders of this exercise are participants of software engineering courses (novice as well as experts), but you can find managerial and communication aspects as well (see Variants below). The mission: The job for the team is to build a bridge connecting the two watersides of a river.

Requirements
? The bridge has to be self-supporting, so no pillars are allowed in the middle of
the bridge.
? Pedestrians shall be able to get onto the bridge from the level of the edge.
?
Of course there is no real river needed for this exercise, two tables that can be moved
around do the watersides for this exercise. The building material for the bridge is
plastic in form of toy Lego building bricks.
Implementation
For the solution of the problem the teams get
? 3 large buckets of Lego building bricks
? Two tables that can be placed in a way that there is up to 150 cm distance
between them (the width of the river)
Development Process
? 30 minutes for planning and prototyping (Prototyping) and
? 5 minutes for the final build from scratch (Construction)
The beginning and the end of the phases is signalled by the instructor (or helper). At
the end of the prototyping phase all Lego parts have to be taken apart again.
After the construction phase, each bridge is tested. It must span the gap for at least
one minute. If more than one bridge passes this test, an additional stress test is
performed: One by one, individual Lego pieces are placed at the middle position of
the bridge. The bridge collapses under the biggest load - i.e. the largest numbers of
added Lego pieces - wins the competition.

If the complete 150 cm shall be connected with the bridge, there is no other solution
like something shown above. If the Lego stones are used in the "usual" way - with the
knobs on the upper side - the connection between the parts is not tight enough to carry
the bridge itself.
The special with this exercise is, that the participants have to get to know this trick.
Before they don't get this, they will build huge buildings and soon run out of parts.
After the teams finish the bridge exercise there is time for a summary for what has
been done. Now the course participants get to know first concepts of software
engineering and project management which can be referred to the just finished
exercise (see the comments on this exercise as well).
Variants
VARIANT V1: Changing Requirements
Stakeholders: Software engineering advancers and experts
To show how the „strong winds of change often blow“ in Software Engineering,
change the requirements 10 minutes time before the planning phase ends - don't tell at
the beginning! Tell the students that there has been a change: The width of the river
has to be 150 cm instead of 50 cm.
Using a width of 50 cm the sudents usually look in the wrong direction - the special
diesng is not needed for such a small width.
When you change the requirements (river is 150 cm broad instead of 50 cm) the
participants will have to rethink their design strategy quickly and most often have to
perform a total redesign of their work.
Include that experience as well into the summary at the end of the exercise. Mention
scalability of systems (also see the WASA example at the end of the slide deck ] ).

VARIANT V2: Team Competition - Two teams in one room:
Stakeholders: Coaches and Managers
Build two teams that start and end at the same time.
Assign bonus points as follows:
1. 10 Points if the built bridge lasts for one minute or longer

2. Number of peaces not needed for the construction of the bridge (so less is
better):
3. A good counting system is to give an additional point for each Lego piece belo
the 60 piece count. For example: 53 pieces needed -> 7 bonus points. 66
pieces -> -4 points.
4. The number of additional pieces that can be placed on the middel of the bridge
during the stress test. The more pieces, the better: One point for each piece the
bridge could hold during the stress test

Note to the instructor:
? Although there is competition, the teams will do collaborative research: If one
team got the 'trick', the other team will follow immediately.
? Include observations about the development and construction process used by
the students into your summary at the end of the exercise. Topics like
nondisclosure and patents could come into discussion as well as design re-use
and design patterns.