Failing to dry out the graduated cylinder between trials. Transferring the sample to the graduated cylinder too quickly and spilling some each trial. Using a beaker (less precise) as opposed to a graduated cylinder (more precise). Not recording enough significant figures each trial (for example recording 1.5 mL instead of 1.52 mL). Incorrectly reading the graduated cylinder marks as 1.0 mL greater than the actual volume each trial. Different students reading the cylinder at different angles each trial. Small changes in the density of water due to tiny changes in room temperature.