http://dcherukhin.i2p/blog/guest/p/10E5CE2CAB/attachments/COR2.html
This awareness grows as children progress from handling single objects, to lining up and ordering objects, to noticing regularities in the arrangement of objects. For example, some patterns repeat (for example, red-blue-red-blue-red-blue), while others change in predictable ways (for example, as age increases, so does height). Working with patterns and relationships is the basis for studying algebra later in school.