To help a 9th grader grasp the concepts of force and the laws of motion, it's recommended to use engaging resources that blend theory with practical applications. "Conceptual Physics" by Paul Hewitt is suggested as a foundational text for understanding the theory behind these concepts. For hands-on learning, "101 Science Experiments" can provide practical experiments that reinforce the theoretical knowledge. Additionally, "Matter, Earth and Sky" by George Gamow is noted for its interesting approach to modern physics, although it may lack in numerical practice. For a book that offers good practice with force numericals, "Conceptual Physics" is a solid choice, although the specific ISBN code was not provided in the discussion.