stimulating budding math kids? (8 yo) My 8 yo child loves maths, he considers it "his hobby". Without pressuring him, I'd like to offer him more challenge, wonder and marvel. The school can't really offer him more (tables of multiplication, yay), and my clumsy attempts aren't helping.
I'm looking for resources/links/references I could use. A youtube maths for kids channel, or books or even a "mothly loot crate" subscription for maths?
Thanks in advance!
Edit: the question got closed (not sure why), but I would like to thank every single person who commented and answered. You've really helped me here!
Edit 2: I've tagged this as a reference-request as per qwr's suggestion. I'd like to keep the question as new good ideas can keep pouring in forever (the boy is 9 now however ;-)
 A: Here are some math books my son has enjoyed:

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*Bedtime Math


*The number devil


*The boy who loved math


*Number Crunch


*Go Figure


*Zero the hero


*Wumbers
Also, we homeschool him and use "Beast Academy", which has an online curriculum for 2nd - 5th that I really like. It has some challenging problems, and some material not typically taught in elementary school in the U.S. It also has puzzles that my son likes.
A: Some ideas:

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*Geometric building toys (zometool, polydron)

*Do some basic computer programming

*Experiment with a graphing calculator (desmos is great, but only 2d)

*Books: Collections from Martin Gardner's Mathematical Games Column (https://en.wikipedia.org/wiki/Martin_Gardner_bibliography#%22Mathematical_Games%22:_The_Scientific_American_columns)

*The Sideways Arithmetic from Wayside School books: https://en.wikipedia.org/wiki/Sideways_Arithmetic_from_Wayside_School

*Various pen-and-paper style puzzles can be found here: https://www.chiark.greenend.org.uk/~sgtatham/puzzles/
A: Here's some ideas I got from trying to get my sister interested in math:

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*Go for geometrical proofs to illustrate concepts. For example, we can prove that a tangent will be perpendicular to a circle by taking the limit as two points of secant coming close to each other. Well demonstrated by Eddie Woo here.


*Try for relatable problems like ones they can grasp through their experience. For example, they are $10$ people in a room, they all meet each other for the first time and want to give an introductory handshake, how many hand shakes occur?
Avoid using variables like $x$ or $y$, and entertain alternate solutions. For example, if you figure out two different ways to solve the above problem, you can figure out a closed form for sum of first n natural numbers.
A problem with this approach is that you have to find out good questions to ask.


*If you are gonna give books (I found books ineffective in my experience), give ones with many pictures.


*There is also this site called Art of Problem Solving. I have never used it myself but I know many friends who had been in that site from a young age and became very good at mathematics. I think the main focus of the site is about Olympiad problem solving.
A: Not a really an answer to your question, but too long for a comment.
I would suggest that you try to widen the scope of his interest, especially more towards 'pure maths': the more abstract topics like set theory, algebra etc. I know - he's only 8 years old and all, and it may sound like absurdly complicated stuff, but I'm not talking about full-on, formal algebra or axiomatic set theory. There is a lot of very useful stuff to learn about the motivations for these things, which will help him when he later gets to the formal maths.
I remember around that age, I started having a real interest in knowing more about the background and playing around with the edges of the concepts I had learned in school, and I found it hugely frustrating that nobody else thought about these things.
For example, when we were doing endless calculations in school to learn long multiplication, I really wanted to know why it worked - there is a simple enough explanation for anyone who is motivated enough to learn; my guess is that your boy would like to explore that.
Or set theory - what is it actually for? This is actually one of the deepest and most fundamental subject in mathematics, and it is a very accessible subject for any child who is interested enough.
