Copper (II) sulphate pentahydrate is a crystalline solid with a beautiful bright blue colour. Like most sulphate salts, it dissolves well in water. If you want or need to separate copper sulphate from sand -- either as a classroom experiment or because you accidentally mixed the one with the other -- you can take advantage of this compound's properties to take the two apart.
Pour the sand and copper sulphate into one of the two buckets.
Pour water into the bucket until it covers the sand and copper sulphate mixture. The copper sulphate should begin to dissolve; stir if you need to make it dissolve more rapidly.
Place the paper filter in the funnel. Holding the funnel over the second bucket, pour the mixture through it. The dissolved copper sulphate will pass through the filter, while the sand will remain behind. The solution you have in the second bucket contains copper sulphate only.
Copper sulphate is often used dissolved in water to kill fungi or algae. If you need to separate the copper sulphate from the water, evaporate the water by heating the mixture or leaving it out in the sun until all the water evaporates.
Copper sulphate may be poisonous if swallowed; it's also an eye and skin irritant. Take appropriate precautions and never leave copper sulphate where children can reach it.