Answer:
Seriation.
Step-by-step explanation:
In cognitive child development, seriation is the characteristic of a child with the ability to arrange things in order of their quality or magnitude. In other words, we can say seriation is the ability of a child to arrange things in a specific order, which could be based on a particular dimensional pattern.
This cognitive psychological skill is a necessary part of a child in his/ her ability to develop numerous concepts like time, numbers, measurements, etc. So, Heather's arrangement of the crayons from shortest to longest is a skill known as Seriation.