Ask HN: Increasingly difficult list of programming questions?

I am currently teaching my friend how to program - she's a very smart girl with a good Maths degree behind her and I've just explained a small bit of Javascript and asked her to implement the FizzBuzz program on codepen. She passed this with flying colours and is hungry for more 'fun' assignments.

I think it would be really great for her to get an email from me each week with a new programming assignment for her to fit into her busy schedule and will encourage her to keep learning.

So are there any fun assignments that you remember doing; I always think doing something real (where you happen to learn fundamentals) is better than saying "off you go learn about object orientation" or functional programming or MVC.

Does something like this exist online or in a book? I've been looking but nothing feels quite right...

Thanks!