Soccer players need to master many concepts in order to play well in training and matches. We need to sort these concepts as players need to learn them from when they are children until they retire. Players go through different stages and in each of them there is content which is more appropriate to be taught than other.
In the initiation stage (U8-U13), players must learn the universal individual fundamentals valid for all positions. In this stage, it is specially important that content is adapted to the boys and girls capabilities. Horst Wein (1941-2016) was one of the pioneers who pointed out the need to adapt training drills and competition systems to children, and not the other way around. Content planning must follow the same principle. For each age group, coaches must select the group of concepts that children can assimilate based on their physical and cognitive capabilities.