35. Evaporation Experiment Directions Partly fill the plastic cups with water so that they both have the same level of water. Mark the levels with the marker. Seal one of the cups with plastic wrap. Leave it for a day. Look at both cups and mark where the water levels are. Do this for a few more days, marking the levels each day and noting any change. Materials 1. 2 clear plastic cups 2. Felt marker 3. Clear plastic wrap 4. Water