What melts ice fastest

A lot of things are similar....

Equipment:
Plastic cups
Water/Ice
Five substances (probably pepper, salt, sugar, soft drink, tomato sauce)
Camera
Measuring cup

Repeat experiment every Saturday to ensure accurate results.

Independent Variables

• the materials placed onto the ice.
  

Dependent Variables

• the melting rate
  

Controlled Variables

• the amount of water is equal.
• the amount of substances is equal.
• the 10 minute time span before re-checking the cups.
• repeating the experiment every Saturday
  
• the amount of sunlight exposure/room temperature
  

Changed my mind.

The experiment I was considering before turns out it won't give out fair results, so I've decided to do what melts ice fastest instead~ Different substances have different effects on ice, some of them cause ice to melt faster than usual.

For the experiment, I'm going to get 6 plastic cups and freeze the water inside until it becomes ice. Then I'll make sure to place them in a dark room so that sunlight will not greatly affect the experiment. Choosing five substances, salt, pepper, sugar, tomato sauce and a soft drink. I'll place even amounts in each of the cups of ice but leave the 6th cup of ice alone. I'll observe the experiment every 10 minutes in order to record results and take photographs.