Marie92

I believe tu is informal and Usted is formal. For instance if you are talking to a friend or someone very familiar you use tu. If you are talking to your boss, an older person, or interviewer you use usted.

Usually, the good old dirty trick to know if you don't want to memorize the list of rules that go with ser and estar is this: estar means temporary status, and ser is more of a permanent status.

So if the knife "está" limpio, it is temporarily clean but can get dirty later.

If ser/es was used, it would be a permanent characteristic that it would always be clean.

Sucio makes a lot more sense. If you use estar to say it is dirty/sucio, it means it's dirty but can be cleaned and fixed. If you use ser, it means it is permanently dirty and irreplaceable, kind of like if you got motor oil on a t-shirt.

Hope this makes sense! 

Thanks for that information. I may have learned it a while ago, but the refresher was great. It makes sense.

nadar - to swim

I originally started taking Spanish because I had to take it in high school, and I grew to love it. Now, I would love to learn it fluently. I have taken a few courses after high school. I think I need more interaction in order to learn it fluently.

I read that the best age to learn a language is very young. When children are young, they soak up information like a sponge. This makes it easier for them to retain information. Therefore, it can become like second nature to them.