Fivesquare,just a little edit there,nothing to worry about.Here it is in basic of basics.More power,more speed,more airflow over wing make airplane climb,less power,less airflow make airplane descend.Eventually,most trainers having postive dynamic stability will try to regain there original flight path,I.E. climbing and descending,climbing and descending for quite awhile until they are almost back to the original flight path.This is where elevator use comes in,if you go to full power without down trim,the plane will climb away simply.Most acro type airplanes have are nuetrally stable,thats why they keep going in what ever direction you leave them until a control input is given,also with the symetrical airfoil they dont care which way is up or down.