It is during this period of time that the appearance of the "social smile" is observed, where the baby responds to the smiles of adults. In addition, they begin to acquire skills through the repetition of satisfactory actions. These actions tend to focus on their own body, rather than on the environment.

They begin to develop repetitive habits and as they coordinate sensory information, they also begin to develop skills such as grasping (Faas, 2021).

Their activity is incessant, they show greater control over their movements by stretching their arms and legs, as well as opening and closing their hands intentionally (Navarro, 2022).

Infants are able to sit upright for short periods of time and transfer objects from one hand to another. They are also able to reach for objects and hold them at the same time. Later, from 5 months onwards, they are able to make an active effort to sit up, which allows them to maintain their gaze and explore their environment (Navarro, 2022).

Around the next month, they acquire the ability to grasp objects with the palm of their hand, marking the beginning of the "floor stage". During this stage, children improve their psychomotor skills as they try to move and grasp objects, thus contributing to motor, sensory and cognitive development (Bachiller, 2012).

At 8 months, babies are often alert, recognise familiar voices and faces. They are able to call tension by shouting and explore their environment by crawling, as they can crawl without difficulty. Between 9 and 12 months, they are preparing to stand up and start walking (Navarro, 2022).

At around 9 months, they begin to stand up and take their first steps. During this stage, acquired sensory-motor schemes are applied to new situations using learned behaviours to achieve specific goals.

By achieving the bipedal position, they can explore their environment more efficiently, accessing places that were previously out of reach. At this age, they begin to show interest in cause-effect relationships between objects (Faas, 2021).

From 24 months, they develop greater motor skills, they are able to walk, run, jump, go up and down stairs and carry objects. It is essential that they learn to control their emotions to avoid constant crying (Navarro, 2022).

They also develop cognitive skills such as remembering, searching, creating and combining actions. They no longer depend so much on trial and error, as they have mental representations of events. Children explore their environment by touching and experimenting with all the objects they encounter (Bachiller, 2012).

From 24 months, they develop greater motor skills, they are able to walk, run, jump, go up and down stairs and carry objects. It is essential that they learn to control their emotions to avoid constant crying (Navarro, 2022).

They also develop cognitive skills such as remembering, searching, creating and combining actions. They no longer depend so much on trial and error, as they have mental representations of events. Children explore their environment by touching and experimenting with all the objects they encounter (Bachiller, 2012).

At 36 months, most children are able to identify their gender and that of their peers. They learn to draw, climb structures and run faster.  

They also show better visual-motor coordination, build towers, grasp pencils and throw objects with greater accuracy, draw simple pictures and engage in physical play to control their aggression (Navarro, 2022).

It is in this period that their balance improves, they can stand for 4 to 8 seconds on one foot, they learn to jump on one foot several times and they practice the "gallop".  From the age of 5, their balance and walking skills are developed (Navarro, 2022).

Faas, A. (2021). Psicología del desarrollo de la niñez. Editorial Brujas.

Navarro Patón, R. (2022). Educación Infantil. Características de la etapa, normativa legal e importancia del movimiento en Educación Física Infantil: Aplicación práctica desde la evidencia científica (pp.17-41). Ediciones Morata.