Here are some websites where you can study for free!

Isn't it great!?

Here they are:

http://study.com

http://www.openculture.com

Apart from them there are also websites already shared with you:

https://www.edx.org  and https://www.coursera.org

Differences between Portuguese and English

http://www.sk.com.br/sk-idiom.html

Here is a great website to learn some English differences:

http://www.dailywritingtips.com

Let's learn some differences betweek American and British English?

Let's learn some differences betweek American and British English?

  

http://www.onestopenglish.com/grammar/grammar-reference/american-english-vs-british-english/differences-in-american-and-british-english-grammar-article/152820.article

Also: http://www.oxforddictionaries.com/words/british-and-american-terms

http://flashcardstash.com/Vocabulary

This is a website where you can check English grammar and vocabulary for business:

http://www.businessenglishsite.com

Here is a website with great videos!

http://www.simpleenglishvideos.com