Early childhood is usually described as the period between 2 and 6 years of age. In other words, early childhood covers children's preschool years (Rathus, 2012). Compared to infants, physical growth in preschool children becomes slower; nonetheless, by the time children reach their middle childhood years, they start to look more like adults and develop excellent motor and coordination skills (Rathus, 2012). In early childhood, children tend to grow 2-3 inches and gain on average 4-6 pounds every year (Rathus, 2012). They become slender and may look rather "unbalanced", as they are reaching their middle childhood years. Despite noticeable variations in the way children grow and gain weight, it is possible to say that, in most cases, boys outpace girls in height and weight gains (Rathus, 2012). These changes lay the ground for the future changes in physical appearance during middle childhood. The latter is the period between 6 and 12 years of age (Skuse, 2003). This is the period when girls' and boys' bones further strengthen, and cellular fluid is gradually replaced by muscle fibres (Skuse, 2003). This is also the period when girls start to outpace boys in bone ossification and skeletal development (Skuse, 2003). During middle childhood, changes in physical appearance become one of the major factors of children's emotional and cognitive wellbeing.