Learn sight words with these sets of digital flashcards (Quizlet sets). There are 10 words in each set.
Here are some lists of the most common words in English. You can go through them to see how many you know and learn the ones you don't.
http://www.englishpage.com/vocabulary/vocabulary.html
Learn some advanced vocabulary and practice using them in context. There are also exercises to help you use the new words with other words that you know to make them easier to remember.
http://dictionary.cambridge.org/dictionary/learner-english/
Learner dictionaries are designed for English learners. The definitions are in easier English and there are examples to show you how to use the new word in context. You can also listen to the pronunciation of the words to learn how to read them aloud.
https://en.oxforddictionaries.com/english-thesaurus
You can find synonyms (words with similar meaning) and antonyms (words with opposite meaning) of a word in a thesaurus. Use it to make your writing more interesting.
https://rewordify.com/index.php
This is a free online tool that helps to simplify difficult words in texts and websites so that you can understand them easily. It also finds all the difficult words, lets you pick which ones to learn, and then teaches them to you. See how to learn vocabulary with Rewordify by watching this part of the YouTube video. Don't forget to turn on the closed caption by clicking on "CC" on the bottom right-hand corner of the video.
Playing games is a great way to learn and revise the vocabulary you have learnt. Come, play and improve your vocabulary here!