Hear is related to Invisible. Invisible is related to Sound. Sound is related to Make. Plastic can be used for Make. 
Plot is related to Farm. Farm is related to Crop. 
Hear <--RelatedTo--> Invisible <--RelatedTo--> Sound <--RelatedTo--> Make <--UsedFor-- Plastic 
Plot <--RelatedTo--> Farm <--RelatedTo--> Crop 