Actually, the problem is a bug and is in the process of being fixed.
Your example is too advanced for a 10 year old. In this example you have to explain what you are simulating using a dartboard example, why you are subtracting 1 from x^2 and y^2, why you are using abs2 instead of abs, that count is not being divided by N*4 and finally why π is nowhere near the result of this function even if you use a sizable N. In the case of the 10 year old, she left the room long ago.
I’m teaching Julia as a first computer language not as an alternative to Python, C or Java.