Define the Procedure for an Experiment
An experiment or series of experiments can make a good science fair project. However such a project is only successful if you keep careful records of all the steps that you followed in your journal. After you have defined the problem and set yourself a hypothesis to test you need to step wise designate the procedure that you will follow.
The procedure can be numbered step wise to make it easier for you to duplicate as often as you wish with a different set of variables. For instance you can use the hypothesis involving how fast an ice sculpture can melt with this set of steps. First form the ice sculpture with normal water, tap water or mineral water. Each of these can be a different experiment in the series.
Now place it outside the freezer to time how fast it melts. This is step two. You can place in indoors, outdoors, during the day and night as your variables. Then measure the temperature at the time you placed it outside. This would be step three. And of course record all the data that you collect in your journal as the last step of the experiment procedure. Fairly easy science project to do and will have excellent data.