Hypothesis

Prediction if my hypothesis is true

Prediction if my hypothesis is not true (null hypothesis)

The thicker the kitchen paper, the more water it absorbs.

Paper A is thicker than paper B which in turn is thicker than paper C. Paper A will absorb more water than paper B than paper C.

Paper B or C will absorb as much water as, or more than, paper A.

The rougher the surface, the hotter it gets when it is rubbed.

Surface A (carpet) is rougher than surface B (lino) than surface C (polished wood). When you rub your hand back and forth five times on surface A it will get hotter than surface B, which will get hotter than surface C.

Rubbing surface B or C, my hand will get just as hot, or hotter, than rubbing surface A.

Colder water freezes faster than hot water.

Container A contains water from the hot tap and container B contains water from the cold tap. When put in the freezer, the water in container B will freeze in less time than water in container A.

Vinegar cleans a coin faster than a soft drink.

Girls have a better short term memory than boys.