Some of our students tried weighing droplets
from pipettes of different sizes, to see if this affected
the size of the water droplet produced. Another group
tried adding oil and soap to the water to see if this
would affect the water tension and thus the size of
droplet produced. One group tried dripping water at
different angles from the pipettes. Some groups
measured the diameter of the droplets produced as
they landed on a non-absorbent workbench, while
others measured the size of stain left by a droplet of
water on a paper towel. One group counted and
collected a large number of water droplets in a scaled
beaker, and then divided the total volume of water
they had by the number of droplets they had collected
to find the size of a single droplet. The fact that there
is no correct answer to this problem mirrors many
problems in real life science. This exercise can be
used as an introduction to a discussion about
variables in experiments, how experiments can be
made ‘fair,’ and overall experimental design.