Please choose the correct ending to complete the given sentence: Education and Communications: [header] How to build a hydrometer [title] Seal off an end of a soda straw. [step] You can plug the end with modeling clay, plasticine (play-doh or cranium clay), or a wad of chewed gum. Be sure to use something that won't let water seep through it, and use a piece large enough not to let water seep past it.

Ending1: [title] Fill the end of the straw with modeling clay. [step] Measure your water supply to the end of the straw with a measuring cup. Ending2: [title] Pour either in or out of the water tank or bucket. [step] Make sure that the water level isn't too high or too low. Ending3: [substeps] Tuck a piece of recycled paper into each straw in order to make sure the straws don't dip up to the surface of the water. Check the bottom carefully after pouring, then attempt to pull it out. Ending4: [title] Fill a narrow jar or graduated cylinder partially with water. [step] If using a graduated cylinder, fill it to the 100 milliliter line.

Answer format: ending1/ending2/ending3/ending4