|Science Olympics 2005: Winter 2005
Popsicle Stick Towers
Kai-Mei Fu and Paul SanGiorgio
This event is a minor variation on the much-loved “popsicle stick bridge” event of years past. Here, though, instead of spanning a certain distance, the students’ towers must reach a certain height. Towers will be tested at the competition with a custom-built tower-breaking machine. They should be able to hold a significant amount of water before breaking.
Popsicle sticks (60 or 80)
Glue (one pack per team of two- may be shared different days)
Kids work in teams of two. Older kids get 80 popsicle sticks per team, younger kids get 60 sticks. Special quick drying glue (sort of a mix between glue and paste) has been bought to help in construction. We won’t set a strict limit on glue use, but we do have a limited number of bottles that must be ordered on-line. Please try to keep an eye out for wastefulness. Broken popsicle sticks and toothpicks work great for administering the glue.
Older kids’ towers must be 11 inches tall (the long side of a sheet of paper), younger kids’ must be 8.5” (the short side). By a quick measurement of the sticks, one can quickly see that the older kids will have to make at least 3 tiers while the younger kids can get away with 2 with a little add-on. There is no requirement on how wide or narrow the base or top must be, but the top must be flat enough to support the particle board on which the weight will be added. This will be tested by laying a flat piece of poster board or cardboard on the top of the tower.
Motivation: Why would someone want to build a tower?
To hold something up
Have them name examples such as (will have pictures for these)
As a monument
Have them name examples
At this point, we want them to start thinking about what elements a successful tower might have. In no particular order, they should have
Try to illustrate these ideas with simple drawings on the whiteboard (draw a tower with no crossbeams, and one with crossbeams, ask which one they think is stronger and why, etc). The other big point to emphasize is the major difference between bridges and towers, namely, towers are more likely to break due to friction (i.e. a joint slipping) than to tension (a stick breaking in half). Thus, they should pay careful attention to their joints.
Now the fun part: two models have been made that should illustrate this point more clearly. One model should be a simple cube and one a cube with diagonal supports. Ask the kids which one they think will be strongest. Ideally, the one with diagonal supports ought to be better (I think), but obviously, you can determine this with the tower-breaking machine. Get the kids to vote and try to reason out why one will be stronger than the other. This is the end of the formal lesson.
Have the students in groups of two. Give them paper and pencil. Attempt to have them draw and decide on a tower plan. Every stick does not need to be drawn- just make sure they have a basic idea of what the tower will look like. Once the tower drawing is approved, hand out the sticks to the group and have fun!