Final answer:
By the end of the first year, an infant should have tripled their birth weight, greatly improved their sensory capabilities, begun teething, and started to develop communication and motor skills such as sitting, crawling, and possibly walking.
Step-by-step explanation:
A normal and healthy infant, at the end of 1 year, should have experienced significant growth and developmental milestones. They generally triple their birth weight and come close to doubling their birth length. Moreover, they should be able to sit, crawl, and may begin to stand or even start walking with help. Infants usually make great strides in their sensory development, displaying improved vision and depth perception. Their communication skills also progress, with the ability to babble, and some may start saying simple words like “mama” or “dada.” They should have developed a set of deciduous teeth and become more interactive, expressing recognition of familiar people and objects through smiles and other expressions. A normal and healthy infant should, at the end of 1 year, have tripled their birth weight and doubled their birth length. By the end of the first year, the average baby is twice as long as it was at birth and three times as heavy. Infants typically start smiling and making vocal sounds at around 6 weeks and babbling at around 6 months. They learn to sit, crawl, and stand during their first year, and may even start walking by 12 months.