I love adding marbles to boys 5-9 and 10-14 boxes.
When I asked my sister, who works with children in Zambia, if they prefered the smaller or the larger marbles, she said most of them had never seen marbles. They play with stones. I know my boys love playing with marbles, they make up all kinds of games with them. And I'm sure the children receiving marbles have lots of fun with them!