Does not show a control or uses too many variables. Experiment doesn't show either chemical or physical changes. Doesn't show understanding of how to develop the experiment. During this lab they will melt and freeze water and observe the temperatures at which these changes occur. As elevation increases the boiling point becomes lower as air pressure decreases.
Phase changes are physical changes because they are reversible and no new substances are formed.
Students should know where fire extinguishing materials are and how and when alcohol burners or bunsen burners are to be lit and extinguished. Warnings about not touching or eating dry ice should be given. Dry ice can cause serious harm, if you are uncomfortable with using it, a slurry of ice, water and salt will give you a temperature well below zero and can be used in its place. It will work more slowly. Goggles should be worn at all times.