All the students in Miss Osbourne's class like pizza. Jeff is a student who likes Pizza. Therefore, Jeff is a student in Miss Osbourne's class. True, Falls, uncertain?

Answer = false. This is like saying,

Everyone in Ireland likes food, bob likes food, therefore bob is in Ireland.

False. That set of statements forms a syllogism

with an undistributed middle.

It's nice that all the students in Miss Osbourne's class like pizza.

You can be sure that if you meet a student from Miss Osbourne's

class, you've met a student who likes pizza.

But they are not an exclusive club. They are not the only students

in the world who like pizza. There are other people in the world who

also like pizza. When you meet a student who likes pizza, he may be

one of those others. He may never have even heard of Miss Osbourne.