Go outside into the snow and collect three samples of snow from three different locations. Make these locations as diffuse as possible, for example you could collect snow from somewhere in direct light, somewhere constantly shaded and somewhere in between. Collect 750ml samples of snow from each location and take them to your experimentation area.
Label three of the plastic cups with an A, three with B and three plastic cups with a C, using a felt pen. Spoon 250ml of snow from the first location into each of the cups labelled A. Repeat this with samples of snow from the second and third locations, transferring the samples into cups marked B and C respectively. Record information about where you found the snow and a description of its condition when you put it in the cup.
Lightly press the snow into each cup with a spoon, ensuring that the snow in each cup is not packed too tightly. The snow in each cup should be lightly packed with gaps in between the different clumps. Make a mark on each cup representing the level of snow. Place the cups in a room temperature environment and allow the snow to melt.
Observe the difference in the level of the water compared to the level of the snow. Pour the water into the measuring jug and observe the volume. Divide the volume of the water by the volume of the snow. This will give you a value for how many times greater the snow volume was to the volume of the melt water. Take an average of this value for each letter and use these averages to find out if different types of snow have different volumes.