Letter is related to Written. Written is related to Design. Design is related to Fashion. Fashion is related to Understanding. 
Block is a type of Collection. Collection is related to Organization. Pool is a type of Organization. 
Letter <--RelatedTo--> Written <--RelatedTo--> Design <--RelatedTo--> Fashion <--RelatedTo--> Understanding 
Block --IsA--> Collection <--RelatedTo--> Organization <--IsA-- Pool 