Which developmental milestone is expected at 18 months?

At 18 months, children typically demonstrate significant advancements in both physical and language development. By this age, most children are able to walk independently, and it is common for them to have a vocabulary of around 15 words. This milestone reflects their growing motor skills as well as their ability to interpret and communicate their needs or observations, marking an important step in their overall cognitive development.

The other options, while indicative of skills that may emerge later, don't align with what is typically expected at 18 months. For example, the ability to run usually develops after 18 months, as it requires greater coordination and balance skills that typically emerge around 2 years of age. Jumping is also a skill that develops later when children have mastered running and balancing tasks. Similarly, while stacking blocks can start around this age, children often can stack only a few blocks (usually 2–3) with more complex skills such as larger tower construction developing closer to age 2 or 3. Thus, walking alone and using a small vocabulary of words encapsulates the key developmental milestones expected at this age.