My daughter went to the district science fair this year

and I saw many easy projects that may work for you. One was testing how long bandaids stick in water. The student used eggs and chose 4 different kinds of bandaid brands. They were stuck on the eggs and placed in water and observed to see how long they stayed on.
Another tested how animal coloring portects them in the wild by using M&Ms.
One more studied the strength of human hair.
How about testing how well materials insulate?
Hope these may help or inspire you.
Michele