1. Have your partner roll a marble towards you across the table.
2. Follow the marble with your eyes as it nears you.
3. Try to anticipate the direction the marble is rolling in.
4. While keeping your eyes on the marble, use your peripheral awareness (side vision) to have cup ready in your lap near the area of the table where the marble will roll from.
5. Catch the marble with your cup.
6. Repeat.