CK-12 (https://www.ck12.org/student/) ‘This is a platform that provides high quality curated STEM content for teachers and students. Its library has over 5000 math and science materials ideal to use in class.
Merriam-Webster (https://www.merriam-webster.com/word-games) - nice collection of games that gets students thinking and improving their lexicon. There are crosswords, cryptograms, word searches, jumbles and a plethora of other brainy games.
Money - http://www.funbrain.com/cashreg/index.html
Advanced Coin Count & Making Change-http://www.mathnook.com/math/countingmoneyadv.html