It is kind of funny, because I initially thought that students would use the index cards to create their towers, but they had their own ideas. I didn't show them any pictures of student constructed projects ahead of time. I just showed them pictures of real towers.
I had asked my class to bring in a cereal or some other small box, but I only gave them a couple days notice and I didn't send home a note. Only about 7 of my students brought in boxes, but this worked out fine. I just threw in foam plates for them to use as a base for stacking.
My students used my STEM Activity - Building a Tower packet for this project. I have created others as well. I've included the links if you would like to check them out.
Build a Habitat
Build a Vehicle
Build a Tower
Build a Robot
Build a Carnival Ride