Alternate ideas....

I have looked up the internet and found many interesting experiment ideas including how permanent are permanent markers in different solvents and brands
, and whether the evaporation is affected by the amount and type of plastic wrap.
My own ideas are investigating the buoyancy of different types and sizes of balloons, and explaining how long it takes for different shapes and brands of soap to dissolve in water.
My preference is the solubility of different shapes and brands of soap. For this I would need at least four beakers filled up with the same amount of water. First, I would experiment with the shapes of soap keeping the brand,room temperature, time in water and shape of beaker the same. Next, I will experiment with different brands and keep the same controlled vraiables, except changing keeping of the same brand to keeping the same shape.The dependent variable would be the cm cubed of the soap dissolved and the independent variable, the shape of the soap. For my next experiment the dependent variable will remain the same but the independent variable will change to the brand of soap.
I can spend approximately 40 minutes per day, one day testing the experiment on the shapes of the soap, and another day testing the experiment on the brands of soap. This experiment will be repeated at least 5 times before the science report is due.
Please comment on your opinions.