Students can investigate the relationship between an ice cube's surface area and how long it takes to melt. This type of project allows a student to not only learn the scientific method, but also work on calculating the surface areas of solids. The student should freeze the same amount of water in each of several containers of different sizes. Each cube has the same volume but a different surface area. The student can measure each cube's surface area, time how long it takes it to melt and graph this relationship.
Fourth graders can investigate how temperature affects the melting time for ice cubes. They should set up environments of several temperatures, including a refrigerator, cold room and warm room. Students can place the same amount of ice in each environment and time how long it takes the ice to melt in each situation. Another way to do the project is to measure how much water melts off of the ice during a specific amount of time in the environment.
Students who live in cold climates that leave ice on streets might want to do a project about the best agents to melt ice. Although rock salt is the most popular, that doesn't necessarily mean that it's the best thing to use. The student can gather several substances to test, including rock salt, table salt, sugar, sand and any other items he wants to try. He should sprinkle the same amount of each one on equally-sized pieces of ice and measure how much ice melts in a certain amount of time or how long it takes to melt the whole piece of ice.
Ice cube projects don't necessarily have to involve melting ice cubes. Another way to study ice cubes is to freeze them. Students can time how long it takes ice cubes to freeze depending on a particular variable. That variable might be the size of the ice cube, the temperature of the freezer or the composition of the liquid being frozen. For example, a student might make solutions with different amounts of salt, sugar or other dissolved substances and measure how long it takes ice cubes of each of these types to freeze.