"A"

As simple as it sounds, the word "a" is throwing me for a loop, and it may be that I have not gotten far enough to learn yet. However if we say "poco a poco" we are saying "little BY little." If we say "a la casa," we are saying "TO the house." So, is this word only interchangeable with to and by, or are there other meanings? Also, these to examples seem pretty easy to decipher, can this get a lot more difficult in advanced Spanish? Thank you,

It sounds as though you're trying to speak Spanish with English grammar rules. Some things are just going to have to be acceptable without trying to figure them out. It's kind of like math. 2 and 2 equals 4. No explanation, just the way it is. You will find that many words in Spanish have multiple uses. If you don't try to figure it out with English, you'll be a lot more ahead in the end. Espero ayudah te

Si, gracias.