I'm a product design student at a school. I need information about the stages of development of a toddler or older (roughly 2-8 years). For example, the stage when a baby begins walking or begins to seize baby actions. 

Sadly each & every child is different so there is no set time scale to see things happen.

Some babies will crawl around 5-6mths, some will not crawl until much older & a few will bypass crawling all together.

Toddling/walking can also begin at any time, some will do this from 9mths but some will not manage it until 18mths.

There are rough guidelines available out there but they are essentially just that - a guide. 

Thank you for your answer