Early childhood online learning encompasses a wide range of topics, such as evaluating the effectiveness of policies for online learning ^[3][27], identifying the need for early childhood educators to carry out distance education during the COVID-19 pandemic ^[4][30], parents’ beliefs and attitudes toward their young children’s online learning during the lockdown ^[5][31], and other challenges of online learning facing children, teachers, and parents during the lockdown.

ECE educators have faced various challenges during the pandemic, including internet accessibility, lack of teacher training to transit to distance learning, technological challenges for distance teaching and communication with caregivers, resources to learning materials, and quality of early childhood programs ^[6][7][32,33]. Another study surveyed 1434 teachers. It proposed five limitations of online learning: (1) difficulties supporting children’s learning and concerns, (2) difficulties with parental involvement, (3) technology issues, (4) social isolation and feeling of being disconnected, and (5) barriers with resources and preparation for online learning ^[8][34].

Furthermore, in ECE, it is necessary to take additional care of children’s development. Psychologists had pointed out that the development of behavioral self-regulation was between the ages of 3 and 7 years ^[9][35], and considerable motivation stability was around 5 years old ^[10][36]. Therefore, researchers believed that although online learning has brought creative and communicative activities for children, prolonged online learning can also come with risks ^[11][12][37,38]. Accordingly, researchers need to meet the social and cognitive needs of children to stimulate their self-regulation ^[13][39], motivation during online learning ^[14][40], and readiness to use digital technology and learning materials ^[15][41]. It is important to draw educators’ attention to these concerns about offering effective and healthy online environments that are appropriate for children to develop their knowledge and technological skills to tackle online-learning difficulties ^[16][42]. Studies proposed the enhancement of digital resources, parental involvement and support, an improved curriculum, communication and guidelines for parents, and more teacher training and collaboration to timely support early childhood educators in reducing their teaching stress and enhancing the quality of online teaching ^[8][34].

Due to the challenges of online learning, parents prefer traditional learning and have a negative belief in the benefits of online learning in early childhood ^[5][17][31,43]. Among studies, Dong et al.’s study has received the most citations ^[5][31]. In theis study, 3275 Chinese parents were polled about their beliefs and attitudes towards their children’s online learning during the pandemic. The results showed that the parents prefer traditional learning in early childhood settings due to three major reasons: shortcomings in online learning, insufficient self-regulation ability of young children, and a lack of time and expertise to support children’s online learning ^[5][31].

Although online teaching brings challenges for young learners, children and teachers can improve their abilities to develop technical knowledge and skills and positive dispositions about online learning and teaching ^[18][45]. For example, many educators adopted social media tools (e.g., Twitter) to build and exchange knowledge, as well as access professional development courses promptly ^[19][46]. Teachers become more creative and raise their acceptance of new technologies, thus providing opportunities for developing online learning activities using technological tools/platforms ^[20][47]. In addition, teachers and children’s families developed a new way to energize their connection with each other, even though the face-to-face connection was missing. In the future, more delivery of teacher-education programs must be considered to update teachers’ technological and pedagogical knowledge to adopt new ways of teaching ^[21][48].

2.2. Physical Activity in ECE during the COVID-19 Pandemic

Due to COVID-19-induced school and park closures, as well as cancellations of children’s sports and activity classes, many children did not meet the recommended levels of physical activity ^[22][20]. A study conducted in the United States found a decrease in children’s level of physical activity during the pandemic relative to before the pandemic ^[22][20]. Another study also found that the pandemic has reduced time spent on physical activity, increased time spent on entertainment screens, and decreased sleeping quality among children ^[23][49]. Young children engaged in less physical activity during the pandemic than before the pandemic, which requires urgent attention from parents and other stakeholders. In the pandemic, children are found to lose curriculum enrichment opportunities (e.g., sharing healthy eating experiences, developing food literacy among children) via an online learning mode ^[24][54]. In addition, the restrictions caused by the pandemic have worsened young children’s daily routines and habits. Therefore, it is suggested that although social restriction is an effective method to reduce the pandemic cases, emphasizing the importance of parents promoting active play with their children is essential to maintain their health and well-being. Although children may not be able to spend time as usual at the playground, green areas, and parks, parents and children could still entertain themselves via indoor activities that do not require a lot of equipment and build a playhouse such as blankets, boxes, towels, balls, and dancing to music.

2.3. Stress and Mental Health in Early Childhood during the COVID-19 Pandemic

On top of physical health, many researchers started to worry about students’ psychological, emotional, and mental health aspects such as depression, stress, and anxiety in the post-pandemic ^[25][26][55,56]. For example, students have experienced various levels of stress, anxiety, and loneliness due to stressful pandemic situations and remote learning, compounded by various factors such as prolonged periods of isolation, higher rates of school dropouts, disconnections from their peers at schools, and lack of family support during home-schooling ^[27][28][57,58]. Moreover, young children (especially those with special education needs) tend to have more behavior difficulties, such as inattention, hyperactivity, and impulsivity, which need additional support from parents and schools ^[29][59]. Family backgrounds seem to moderate the COVID-19 effect on child well-being. According to Mochida et al.’s study with 1030 caregivers, the children whose mothers have lower education levels undergo a significantly higher level of psychological stress than children with higher maternal education levels ^[25][55]. Furthermore, children from low-income families have significantly higher psychological stress than children from high-income families ^[25][55]. Furthermore, children who cannot attend kindergarten or daycare due to the pandemic have higher levels of psychological stress than those who attend kindergarten or daycare daily ^[25][55]. Therefore, the family backgrounds of children and access to kindergarten or daycare greatly impact children’s level of stress during the pandemic.

2.4. Families in Early Childhood Research during the COVID-19 Pandemic

Children are home-schooling due to school closures during the pandemic. Consequently, parental involvement in ECE becomes even more critical. Researchers identified that parents are more engaged in their children’s schooling and schoolwork during the COVID-19 pandemic ^[30][61]. Active parental involvement could reduce children’s negative learning behaviors such as inattention, procrastination, and hyperactivity. Some researchers have investigated how parents provide home education for their children at the kindergarten level during the pandemic ^[31][62]. The Guttman Scale questionnaire was used as the research instrument in Hapsari et al.’s study, which shows that parental involvement in ECE during the pandemic is accomplished through the following strategies ^[32][63]: nurturing, two-way communication, home learning strategies, and decision making. During the COVID-19 pandemic, parents have been more active in providing home education for their children; however, home environment-related limitations could hinder the possibilities of quality home-schooling, especially in families with lower income ^[17][43].