I have done a few variations of this project with different grade levels.
It is always a big hit with the students.
I introduce a variety of architecture. We talk about different styles of houses and the differences between rural/suburban buildings and urban buildings where verticality is emphasized. This time around I introduced images of the Taj Mahal, St. Basil's Cathedral, some of Frank Geary's building designs, and others. The students were especially fascinated by the 'hershey kiss' shapes atop the towers.
If possible we use the larger construction paper 18" x 24" if we have enough work room.
I use this opportunity to teach the students about TINTS and how when colors are blended with white they really pop out from a darker background.
Most recently I did this project with my fourth grade class who I happen to have a for a full hour NOT 30 minutes like my other classes. The teacher whose room we hold class in also happens to be extremely hospitable with her classroom. These pictures show how a regular classroom can become an enthusiastic art class when the right circumstances come along!
Here are some examples of how I've done the project in the past.
(The uber-purpley ones were from a summer class of all third grade girls.)