class Browser < Canvas 
 field :version, type: Integer 
 scope :recent, where(:version.gt => 3)
end

message:
  Defining a scope of value #<Mongoid::Criteria:0x00007face0236ba0> on Browser is not allowed.
summary:
  Scopes in Mongoid must be procs that wrap criteria objects.
resolution:
  Change the scope to be a proc wrapped critera. Example:
   class Band
     include Mongoid::Document
     scope :inactive, ->{ where(active: false) }
   end

class Browser < Canvas    
  field :version, type: Integer    
  scope :recent, ->{ where(:version.gt => 3) }
end