Educational toys claim to enhance intellectual, social, emotional, and/or physical development. Educational toys are thus designed to encourage reasonable development milestones within appropriate age groups. For preschool age youngsters, simple wooden blocks might be a good starting point for a child to begin to understand causal relationships, basic principles of science (e.g. if a block falls from the top of a structure, it will fall until a surface stops its fall), and develop patience and rudimentary hand-eye coordination. For a child moving towards elementary school, other, more sophisticated manipulatives might further aid the development of these skills. Interlocking manipulative toys like Lego or puzzles challenge the child to improve hand-eye coordination, patience, and an understanding of spatial relationships. Finally, a child in elementary school might use very sophisticated construction sets that include moving parts, motors and others to help further understand the complex workings of the world. Importantly, the educational value derived by the child increases when the educational toy is age appropriate.