Puzzle page, which has videos and puzzle writeups: mathforlove.com/puzzles
Geek for Geeks puzzles: https://www.geeksforgeeks.org/puzzle-2-find-ages-of-daughters/?ref=lbp
Mancala game: https://www.mathsisfun.com/games/mancala.html
IMAGINARY Learning: https://www.imaginary.org/program/surfer, https://imaginaryorg.notion.site/Let-s-talk-about-outreach-6c16df49c3eb415cb7b383d2f9df5260
Julia Robinson Mathematics Festival: https://www.jrmf.org/activities?isMultiplayer=1&sort=publishedAt_DESC&tab=1
Rich Learning Series with Dan Finkel: https://mathspathway.com/media-library/category/richlearning/
Nurturing young Mathematicians https://nrich.maths.org/pakistan2024, https://nrich.maths.org/15208, https://nrich.maths.org/15287 https://nrich.maths.org/15369 https://nrich.maths.org/1866 https://nrich.maths.org/15110
Math Pickles at MOMATH: https://mathpickle.com
Global Math Project: https://globalmathproject.org/
Videos Rich Tasks: https://mathforlove.com/video_category/rich-tasks/
One link that I think might be quite useful is playwithyourmath.com.
Purple Cornet! Math Meet (https://purplecornet.org/): Taking place around the world in April, Purple Cornet! Math Meet is a free, online, international, team mathematics competition designed for middle and high school students conducted annually since 2003.
Canada Cyber STEAM Challenge (C3) (https://canadacybersteamchallenge.com/): The Canada Cyber STEAM Challenge (C3) is a national online competition aimed to encourage students in grades six through twelve to develop innovative solutions to real-world problems involving science, technology, engineering, arts, and math.
Education.com (https://www.education.com/): A Limited number of worksheets are available for free, which you can use and your students to enjoy.
Games 4 Gains (https://games4gains.com/): Require creating a free account. Several worksheets are available for free, others may require paying some fees.
Po Shen Loh (https://www.poshenloh.com/live): Free daily YouTube Live Stream. It’s an “Ask Math Anything”, taking any middle/high school math questions serving the wider public.
The Centre for Education in Mathematics and Computing (CEMC - Waterloo) (https://www.cemc.uwaterloo.ca/resources): The CEMC courseware materials feature lessons, interactive activities, enrichment challenges, and unlimited opportunity for practice with feedback. The courseware is online, free to use, and does not require registration.
Parallel by Simon Singh (https://parallel.org.uk/): Weekly math challenges. 15 minutes of interesting, fun and challenging material that goes beyond school math: mystery and history, activities and oddities, puzzles and problems.
Problem of the week – NCTM (https://www.nctm.org/pows/): The National Council of Teachers of Mathematics (NCTM) posts weekly math problems for each and every student.
Math is Fun (https://www.mathsisfun.com/): Free worksheets and math games for all levels.
Cool Math 4 Kids (https://www.coolmath4kids.com/): Free math games, lessons, quizzes, manipulatives, brain teasers and more for kids, teachers and parents.
Perimeter Institute for Theoretical Physics (https://insidetheperimeter.ca/stay-at-homescience-for-explorers-of-all-ages): Offers a list of STEM interesting activities beside math.
The Magical Way to Learn Mathematics (http://zimmer.fresnostate.edu/~mnogin/fresnomathcircle/magictricks/powerof3.html): Many playing card tricks and the math behind them that will amaze your students.