Attributes are characteristics of a set of items that allow the items to be sorted and classified.  (Learn Alberta)

Representing a situation or solving a problem concretely means doing so using actual objects.    (Learn Alberta)

Conservation of number is a mathematical concept that was first identified by Jean Piaget in the mid twentieth century. It is the recognition by a young child that quantity does not change with physical rearrangement. (Google defn)  Ex.  3+2 is the same as 2+3

Definition: Conservation : The understanding that something stays the same in quantity even though its appearance changes. To be more technical (but you don't have to be) conservation is the ability to understand that redistributing material does not affect its mass, number or volume.  (http://www.simplypsychology.org/concrete-operational.html)