DURING A SUPERVISED SOLO CROSS COUNTRY, THE FLIGHT WAS DIVERTED FROM THE PLANNED FLIGHT ROUTE. THE PILOT STATED THAT FUEL CONSUMPTION WAS GREATER THAN WHAT SHE HAD PLANNED FOR. THE PILOT SAID SHE REALIZED THE AIRPLANE DID NOT HAVE ENOUGH FUEL TO MAKE HER NEXT DESTINATION, SO SHE STARTED TO DIVERT TO AN ALTERNATE LANDING SITE. SHORTLY THEREAFTER, AT APPROXIMATELY 2,000 FEET MEAN SEA LEVEL, THE ENGINE QUIT. THE PILOT MADE A FORCED LANDING IN A FIELD. THE ON SCENE INVESTIGATION REVEALED THERE WAS NO FUEL IN THE FUEL TANKS. THE PILOT REPORTED THERE WERE NO AIRPLANE MECHANICAL MALFUNCTIONS. THE PILOT STATED IN THE RECOMMENDATION SECTION OF THE ACCIDENT REPORT, ' (1) THINGS DIDN'T GO AS PLANNED: PLAN FUEL STOPS FOR WORST POSSIBLE SCENARIO, AND (2) MONITORED MORE CLOSELY THE TIME SPENT IN THE AIR INSTEAD OF WHAT THE FUEL GAUGES READ.' THE PILOT'S FLIGHT INSTRUCTOR STATED THAT HE ASSUMED SHE WOULD REFUEL AFTER THE FIRST LEG OF THE FLIGHT. THE FLIGHT INSTRUCTOR STATED, IN HINDSIGHT, HE SHOULD HAVE BEEN MORE SPECIFIC ABOUT WHEN AND WHERE THE PILOT SHOULD REFUEL.