"El gato duerme sobre el perro."
The cat sleeps upon the dog should be acceptable. Sobre means on, on top of, upon
Any idea why the following is not acceptable, as present can indicate this also: The cat is sleeping on the dog. I know this could be "está durmiendo or whatever also but I feel both express same idea.
I agree with you. The present indicative in Spanish could be interpreted as she sleeps, or she is sleeping. English use the gerund much more frequently.
I believe soñar is to dream and different from dormir, to sleep, similar to english.
I think that sobre, encima de, etc should be taught separate of por and para. That way it is better to learn the differences of por and para and how to use the directions.