Tackle is a different concept from Guard. Guard is related to Private. Private is related to Property. Property is related to Area. 
Age is related to History. History is related to Class. Freshman is a type of Class. 
Tackle <--DistinctFrom--> Guard <--RelatedTo--> Private <--RelatedTo--> Property <--RelatedTo--> Area 
Age <--RelatedTo--> History <--RelatedTo--> Class <--IsA-- Freshman 