What are 2 ways to separate a mixture of sand and rocks

You can sift through them with a sort of sifter, like little kids use at the beach. You can literally blow on the rocks, and the sand will go away, but the rocks won't.

dissolve it water and filter it through paper. The sand will be in the paper and then sugar will be dissolved in the water. you can let the water evaporate and you will have the sugar back.