Joan wants to test if salt lowers the temperature at which water boils. in two or more complete sentences, describe the best way for joan to develop a hypothesis for this situation.

In order to build a hypothesis, Joan should take an educated guess at what the effect of adding salt to the water will be on the water's boiling point. For example, the hypothesis may be,"The boiling point will increase". This hypothesis is one that can be verified or rejected via experimentation. The next step for Joan would be to set up an experiment to test this hypothesis. 

The rocks expand when there hot/warm  and contract when they are cold.