Super marble

I saw a kid aged eight walk into a party with a book. I half expected it to be 'The Diary of a Wimpy Kid'. I asked him if he knew how to play the game of Marbles. He didnt. I explained what I knew of it. Later I found him reading the book. Asked him for a summary. He told of a competition between Arthur and Grandma. Arthur learnt the game from Grandma but she hasnt taught him all the tricks. Then he asked me to guess who wins. I said grandma and then recalled the title 'Arthur loses his marbles'.