Want to get kids excited about engineering? Have an extra class before vacation? This is an accessible challenge to which I have added the opportunity to formulate a hypothesis, record results, and evaluate your findings. You can do this activity with brand new paper, but it is a great opportunity to make use of scrap paper from the copy room. Ask people to start saving it now.
With time for practice and to discuss the parameters and constraints, this activity takes at least two class periods. If you are pressed for time, that could be as little at 1.5 hours and you could probably fill 2 hours or more, if you allow time and materials for iterations and improvements.
Twenty sheets of paper is a good number to use. With 20 sheets, some students will create structures that will be taller than they are, and in the past I have had structures nearly reach the classroom ceiling. Copy paper is nearly 30 cm on the long side, so double or triple that height should be a reasonable goal for every student.
When it comes time to test the structures, have the students begin with their structure on a smooth floor, not carpeting. You can measure the structures on a table on the floor, depending on how tall they are.
There are several possible extensions for this activity. You could investigate aerial antennas and the different methods used to build them. You could investigate the tallest buildings in the world and the forces architects have to consider when designing them. You could assign costs to each of the materials and calculate the tallest building per dollar spent. You could have students work in groups and practice their collaboration skills. You could test the relative strengths of different papers (construction vs. copy paper), and you could use a fan to apply a force to the structures to add a design parameter.
This activity works well on its own and as a part of an engineering curriculum. I have a second similar activity in which the challenge is to create a structure that can bear the most weight. Either makes a decent activity for a substitute teacher, but you may not want to miss the fun.