Answer:
hypothesis
Step-by-step explanation:
This is a hypothesis. 
A hypothesis is a simple scientific guess into nature usually drawn from succinct and detailed inquiry into the nature. 
It is usually preceded by observation making and asking of questions. 
Now, we formulate a testable and falsifiable hypothesis which experiments can prove or disprove. This will then lead to the formation of either a theory or law. 
The student is predicting from his observation that if the rubber tubing replaces wire, current will not flow.