Ditch That Textbook Matt Miller's List (awesome!):
https://ditchthattextbook.com/10-sites-for-students-with-free-time-on-their-hands/Â
Sudoku - put all numbers 1-9 in the empty boxes such that each column, row, and 3x3 box has the numbers 1-9 only once in them.
Search "web sudoku"
Logic Puzzles - use the clues to figure out which item/time/place/characteristic belongs to whom using the grid provided.
Search "logic puzzles"
Search "brain bashers"
Puzzle Sites (There are multiple links on these):
Search "math is fun puzzles"
Search "transum puzzles"
KenKen - This is like Sudoku and magic squares put together. There are operations and numbers to fill out a compact area of empty boxes.
Search "kenken puzzle"
Crosswords - Use the short clues to put a synonym or phrase or missing blank in the empty boxes.
Search "dictionary crossword"
Search "boatloadpuzzles play crossword"
Riddles - self-explanatory
Search "math riddles"
Minesweeper - Click on a gray box. The number that shows tells you how many bombs are around that square. If you hit a bomb, you blow the game up and die. If the square remains blank, then it touches no bombs. If you right click, then you can mark and plan out where the bombs are.
Search "birrell minesweeper intermediate"
Make 24 - you must use EVERY number:
Search "4nums" or "make 24"
General Logic Puzzles:
Search "uen interactives brain teachers"
Site with bunches of organized by topic games and math practice:
Search "oates math weebly math games"