Final answer:
Babies typically start to crawl and sit unsupported by about ten months, exhibit stranger anxiety around six months, and may wave goodbye around the end of their first year. They can pull themselves up to stand and walk with help at around one year old. These milestones also include cognitive developments like responding to simple commands and increased language skills.
Step-by-step explanation:
Developmental Milestones in Infants and Toddlers
Babies reach key developmental milestones at various ages, including the ability to sit steady unsupported, crawl, and pull up. By about ten months of age, infants are usually able to wiggle and crawl, and they can sit unsupported. They can pick up objects with a pincer grasp and may exhibit anxiety around strangers.
By six months, infants are generally able to sit up and reach for toys, showing early signs of stranger anxiety. The ability to wave goodbye might come by the end of their first year, as they are also likely to stand while holding onto objects and may begin to walk. By one year, children can follow simple commands such as 'wave bye-bye' which also indicates an understanding of object permanence
Toddlers, by their first birthday, can pull themselves up to a standing position and walk with assistance. They gain fine motor skills necessary to perform actions like rolling or tossing a ball, and show separation anxiety when away from parents. As they approach their second year, their vocabulary increases, and they respond more to simple verbal commands.