Final answer:
At 12 months old, infants like Cassie can typically stand while holding onto objects and may start to locomote by taking steps with or without support. They develop these gross motor skills at their own pace, with some children walking as early as 10 months and others later.
Step-by-step explanation:
How 12-month-old Cassie Would Locomote
By the time infants reach 12 months of age, they typically exhibit significant improvements in locomotion. At this stage, many infants like Cassie are able to stand while holding onto furniture or someone's hand. They are beginning to take steps and may even start walking with or without support, as seen in Figure 23.5.11 where a one-year-old uses a push toy for balance. At 10 months, as depicted in Figure 23.5.10, an infant would have just learned to crawl. Thus, it's common for 12-month-old infants to locomote by crawling and may also walk using objects or people for support.
Physical development in toddlers like Cassie includes gaining the gross motor skills necessary for bipedal locomotion, such as pulling themselves to a standing position, walking with help, or independently. These skills allow children to explore their environment more fully and interact with objects and people around them. By each child's second birthday, they typically can run and walk up and down stairs while holding on. However, it is essential to remember that children develop at their own pace, and some may start walking as early as 10 months, while others may take a bit longer. Concerns about a child's development, such as not walking by 15 or 18 months, should be discussed with a healthcare professional.