When do you use a la for je vais sentences and au ex. cinema?

You're right to be asking! The difference between "à" and "au" before "cinéma" is a key part of French grammar. Here's the breakdown:

"à" is used when:

* The word following it is feminine: Je vais à la librairie (the bookstore).

* The word following it is masculine and starts with a consonant sound: Je vais à l'école (school).

"au" is used when:

* The word following it is masculine and starts with a vowel sound: Je vais au cinéma (the cinema).

Why the difference?

This is a bit of a quirk of French pronunciation. "Au" is a contraction of "à le," but the "e" at the end of "le" is silent when it's followed by a vowel sound.

In summary:

* Masculine noun, vowel sound: "au"

* Masculine noun, consonant sound: "à"

* Feminine noun: "à"

Let me know if you have other examples you'd like to explore!