Questions about saber and conocer
Q: Why is it él conoce al profesor and NOT él sabe al profesor?
R: The verb conocer is used when you mean "to know" or "be familiar with" a person.
Q: Why is it conocemos a ellos and NOT conocemos ellos?
R: You must use the personal a before a noun or pronoun that refers to a person.
Q: Why is it ustedes saben dónde está la oficina and NOT ustedes conocen dónde está la oficina?
R: Remember, if the following word is a question word like dónde, always use saber. Conocer CANNOT be followed by a clause or an infinitive.
Q: Why is it El niño sabe hablar español and NOT El niño conoce hablar español?
R: Since the phrase is about knowing how to do something (speak Spanish), you should use saber. In general, use saber if the following word is an infinitive.
Q: Why is it los estudiantes saben la lección and NOT los estudiantes conocen la lección?
R: You should use saber before a noun if you mean to have learned something. Use conocer before other nouns like people and places.