Answer:
1. Models and theories should explain known fact.
2. Models and theories should enable scientists to make accurate deductions and predictions.
Step-by-step explanation:
A model involves the use of a physical, conceptual, or mathematical representation to describe a real phenomenon that could not be understood by mere direct observation. It could be in the form of a diagram or picture, aircraft model kit etc.
A theory is a well tested and confirmed phenomenon through repeated observations and experiments. It is a stronger assertion that explains the facts about a phenomenon. Such are not guesses or mere saying, but reliable accounts of some phenomenon in the real world.
Therefore for models and theories to be valid, they must explain known facts and enable scientists to make accurate predictions.