Machine is related to Gear. Gear is related to Helmet. 
Working is related to Activity. Activity is related to Grow. Grow is related to Field. Campus is a type of Field. 
Machine <--RelatedTo--> Gear <--RelatedTo--> Helmet 
Working <--RelatedTo--> Activity <--RelatedTo--> Grow <--RelatedTo--> Field <--IsA-- Campus 