The list below is from

www.TextProject.org.  It provides a list of 4,000 Simple Word Families that make up 90% of all texts! When choosing vocabulary words to teach, cross-reference words from class texts with this high frequency word list to ensure that you’re choosing vocabulary students will encounter regularly. If a word is not on the list, but it still seems that it will be a high utility word, check the rank using www.wordandphrase.info. First, go to the “Frequency List.” There you can enter the whole word,or the word part.  Still not there?  Consider using a higher frequency synonym.