Paper aeroplane investigation

In science club our next challenge is to investigate the best paper aeroplane.  Each group can only investigate one aspect of a paper aeroplane for example it's size, material or the shape of the wings.  we have already designed some planes.  We now need to to think about how we will conduct a fair scientific test.

What variable will you change?

How will you record and present your results ?

How will you make sure the test is fair?

How will you make sure the test is safe ?