Search is a type of Activity. Fish is a type of Search. Fish is related to Sea. Sea is related to Source. 
Glad is related to Bag. Bag can cause/lead to Travel. Push is a type of Travel. Push is a type of Approach. 
Activity <--IsA-- Search <--IsA-- Fish <--RelatedTo--> Sea <--RelatedTo--> Source 
Glad <--RelatedTo--> Bag --Causes--> Travel <--IsA-- Push --IsA--> Approach 