Number Concepts: Counting, recognising and using numerals correctly, comparing numbers and operations on numbers are considered as important milestones in the development of number concepts.

One-to-one Correspondence: It refers to the concept that each object is counted only once.

• First assigning a number to a particular object which forms one of a sequence of objects is known as ordinal aspect of number. Ordinality refers to the order (what is the position?) of the objects in a collection. Ordinality develops earlier at about 3 to 5 years of age after the child is able to match the objects in two collections using the method of one-to-one correspondence along with the knowledge of number names.
• The second and final step of counting is of knowing that the number of objects in a collection (‘manyness’, or ‘numerosity’) i.e. the cardinal aspect. Cardinality refers to the size (How many objects?) of the collection.

Hence, we conclude that one-to-one correspondence is one of the aspect of number sense.