What is the estimated age of a child who can walk up and down stairs alone and has a vocabulary of about 300 words?

A child who can walk up and down stairs alone typically demonstrates advanced gross motor skills and is usually around 24 months old. At this age, children become more confident in their ability to navigate their environment and control their body movements, which includes climbing stairs.

In terms of language development, a vocabulary of about 300 words is consistent with a 24-month-old. By this age, children often begin to combine words into simple sentences and show an increased interest in communication, which aligns with the developmental milestones expected for toddlers.

Overall, the combination of physically walking up and down stairs and having a vocabulary size around 300 words accurately reflects the skills typically developed by children around 24 months of age.