Which sentence states a fact?
Dione Lucas was the first woman to graduate from the cooking school Le Cordon Bleu in Paris. Graduates of the Parisian cooking school Le Cordon Bleu make the most delicious meals.
A fact is something that can be proved by research or observation.
Napoleon Bonaparte was shorter than King Louis XVI.
The statement above is a fact. The statement can be proved by researching the height of each man and comparing them.
An opinion is something that a person believes, thinks, or feels. An opinion cannot be proved.
Napoleon Bonaparte was a better leader than King Louis XVI.
The statement above is an opinion. People can have different ideas about what makes someone a "better" leader, so the statement cannot be proved.
The first sentence states a fact.
Dione Lucas was the first woman to graduate from the cooking school Le Cordon Bleu in Paris.
It can be proved by reading about the history of Le Cordon Bleu.
The second sentence states an opinion.
Graduates of the Parisian cooking school Le Cordon Bleu make the most delicious meals.
Most delicious shows what a person believes, thinks, or feels. Another person might have a different opinion about what counts as the most delicious meals.