Conducting an experiment to find out if the shape of an ice cube affects how quickly it melts is actually exploring whether surface area affects the melting rate. During this experiment, maintain the same water volume, freezer temperature, room temperature, water source and container material for each sample to isolate the effects of shape on the ice cubes' melting rates.
Develop a hypothesis about the project before you start. What do you think will happen and why? Although the volume of two ice cubes may be the same, their shape may change their melting rate because different shapes produce different surface areas. Ice cubes with more surface area have more ice exposed to the outside, while those with less surface area have more of the ice contained inside.
Gather several plastic containers that you will use to make your ice cubes. The containers should all have different dimensions so that each ice cube has a different shape. Using rectangular containers will allow you to calculate the surface area of the ice cubes more easily later in the experiment. You'll also need a stopwatch, a thermometer, a measuring cup, containers to melt the ice cubes in and a notebook to record your data.
Pour an equal amount of water into each of your plastic containers. Measure carefully to ensure that each container holds exactly the same volume of water. Place the containers of water in the freezer for 12 hours. Remove the first ice cube from the freezer and start a stopwatch. Quickly record its length, width and height measurements. Place it in a container to melt and stop the stopwatch when it has melted completely. Repeat the process for the rest of the ice cubes.
If different-shaped ice cubes melted in different amounts of time, you have already proven that the shape does affect how quickly it melts. But to find out how the shape affects it how much difference it makes, you also need to know the surface area of each ice cube. Use the formula 2ab + 2bc + 2ac, where a, b and c are the dimensions of the ice cube, to calculate the surface area. Put your data into a chart to see the correlation between the surface area and the time taken to melt the ice cube.