them to figure out how they can be used. By approximately 2 years of age, toddlers develop symbolic thinking and the capacity to solve problems mentally rather than exclusively through trial and error (e.g., ability to place a square block into a square hole). In Piagetian terms, by mid-toddlerhood they progress from the sensorimotor period of relying on their senses to the preoperational period of figuring out how things work or how they come apart. Applying imitation and exploration through active play enables toddlers to learn and to develop autonomy and a sense of mastery – understanding their environment through their own actions.
The desire to explore and touch is so strong that toddlers will repeatedly touch things, even if warned that the objects are dangerous or off limits. Toddlers often strive to engage in activities and touch things that they observe family members doing even if they lack the prerequisite skills. Consequently, the prevalence of unintentional injuries is high during toddlerhood. In 2018, the prevalence of deaths due to unintentional injuries among 2-year-old children in the United States (9.9/100,000) exceeded the prevalence of deaths among children aged 4–15 years more than twofold (3.9/100,000), with deaths among 3-year-old children at 6.7/100,000 [10]. It was not until children reached 16 years of age (the age when youth can obtain a driver’s license) that the prevalence of deaths exceeded that of toddlers (11.4/100,000). Although toddlers are increasing in mobility, exploration, and problem-solving skills, their ability to recognize danger is not well developed, and their risk of injuries is high. Thus, toddlers require careful supervision to avoid potential hazards, often within their home.
Language
Toddlers’ language skills increase along with their advancing cognitive skills. Toddlers in multilingual settings learn to understand and speak multiple languages, and most toddlers are speaking in sentences that can be understood by nonfamily members by age 3 years. Toddlers also use their language skills to engage in pretend play, often re-enacting situations that they observe in daily life. Their ability to use symbols and imagination to engage in pretend play enables toddlers to re-enact household issues or to practice make-believe interactions with others.
Advances in language include both the number of words that children understand and speak and also complex language-specific structures. Children benefit from language-rich environments, based on contingent language in which caregivers talk about what the toddler is experiencing, and build reading into daily routines. Dialogic reading, with books becoming a stimulus for turn-taking conversations between toddlers and caregivers, has been shown to promote literacy in multiple countries [11]. Dialogic reading is the basis of Reach Out and Read, a program that has been implemented globally in homes (www.reachoutandread.org).
Sleep
Sleep patterns consolidate during toddlerhood as toddlers sleep through the night with a mid-day nap and shift from cribs to beds [12]. The American Academy of Pediatrics recommends that toddlers receive 11–14 h of sleep daily with bedtime before 9:00 PM [13]. Toddlers who receive less than the recommended amount of sleep are at increased risk for excess weight gain, emotional dysregulation, impaired growth, injuries, and lower academic achievement. In addition, shortened nighttime sleep increases the likelihood of next-day sedentary behavior [14]. With the exception of sleeping, toddlers should not be sedentary or inactive for more than 1 h at a time.
Attachment and Separation Anxiety
Infants differentiate familiar from unfamiliar people and form attachment relationships with primary caregivers that continue into toddlerhood [15]. Toddlers often use attachment relationships as a “secure base” to explore new situations. That is, knowing that the attachment figure is nearby, toddlers feel secure exploring new situations. Toddlers may also experience separation anxiety and feel anxious when primary caregivers are out of sight, illustrating a lack of understanding that the separation is temporary. Separation anxiety can be stressful for toddlers and their caregivers, particularly because toddlers may also experience frustration when they are reunited with their caregivers, particularly if they are temperamentally “difficult.” In most situations, separation anxiety abates as toddlers gain more sophisticated object permanence skills and comfort in dealing with novel people and situations.
Temperament refers to children’s personality or behavioral style in handling situations. The 3 primary domains of temperament are “easy,” “slow to warm up,” and “difficult.” A child with an easy temperament goes with the flow, adjusts to changes in patterns of eating, sleeping, and playing without difficulty. A child with a slow-to-warm-up temperament may be hesitant initially but slowly adapts. A child with a difficult temperament has trouble adapting to changes or new situations, and may be negative and difficult to handle. Although temperament is thought to be intrinsic in nature, caregivers can learn to manage their toddler’s temperament by providing opportunities for the toddler to experience success and learn to adapt to novel or changing situations.
Autonomy and Independence
The acquisition of multiple skills, along with a desire to explore and model what they observe, contributes to toddlers’ sense of autonomy. As their mobility increases, toddlers want to do things themselves, often without help from others. Effective caregivers have rules for toddlers to enhance their development, to socialize them as family members, and to protect them from potential dangers. When toddlers perceive that rules are in conflict with their independence, they experience frustration. With their need to rely on caregivers, and their limited impulse control, temper tantrums can result. Temper tantrums are difficult for toddlers and caregivers. With effective management, often by helping the toddler focus on developmentally appropriate activities, temper tantrums can be prevented. As toddlers mature and acquire more cognitive and self-regulatory skills and better impulse control, their ability to handle autonomy and independence improves, and temper tantrums can be averted.
In summary, child development is cumulative and dynamic during toddlerhood, building on skills acquired during infancy. Gross motor advances (crawling, walking, running, and climbing) enable toddlers to explore their physical environment as they engage in goal-directed behavior. Fine motor advances enable toddlers to pick up small objects, manipulate eating utensils, and self-feed. Oral motor and language developments enable toddlers to chew complex foods, to express themselves and communicate, and to negotiate. With enhanced cognition, toddlers can solve problems, recall the location of hidden objects, and play simple games. Toddler’s social development includes prosocial skills, such as empathy and recognition of others’ emotions, and self-regulation, such as controlling their thoughts or behavior in response to specific contexts and situations. These emerging skills bring increasing autonomy, often accompanied by impulsivity to satisfy their desires immediately. When combined with toddlers’ changing nutritional needs, their increasing autonomy can present challenges to caregivers, especially during meals.
Toddler Eating Behavior
The World Health Organization recommends exclusive breastfeeding of infants until approximately 6 months of age and then transition to complementary feeding, defined as the period when breast milk alone is no longer sufficient to meet infants’ nutritional requirements. Complementary feeding extends from approximately 6 to 18 months well into toddlerhood. Breastfeeding often continues in the second year as food occupies an increasingly larger proportion of toddlers’ diet. Guidelines for complementary feeding have focused primarily on toddlers’ nutrient requirements and advances in flavor and texture as their diet expands and begins to approximate the family diet [16].