Lads its simple..
Biol. - Just get the % of the plants that grow from the fridge and without, or if one is faster, ie without doing it we know the hotter one will grow faster because thats one of the main factors that a plant needs to grow.
Cem. - Pure the fizzy drink into a long measuring tube and when you pour it in the gas will rise to a certain number, take the number down and take the ml's you have in hte start ie 330ml in a can...youll have the amount of gas from the drink.
Pysics - get different cups, ie plastic glass srl. put a thomometer in each glass and see how long it takes for each one to get gradually colder.
Sorry i cant use an scientific terms as i go to an irish school.... but hope this helps anyway