Cotton is an isulator because it does not transfer electric charge easily:) :)
five common materials
From the top of my head: Ceramics, most plastics, wood when it is dry , mica, Kraft paper, resin bonded fibre or paper
Insulators are found on the right side of the periodic table, specifically in the nonmetals and noble gas groups. They have high resistivity and do not conduct electricity or heat very well due to their electron structures.
the controlled variable is the same thing that is used so say if you where testing isulators you could see if paper or if saw dust is a better insulator the controlled variable in that test is the thermomiter and the ice cube in the insulators and the ice cube a room tempeture.
It depends what the peg is made of. Mine are mostly plastic or wood, which are insulators. However, many have metal springs, and metals conduct.