Final answer:
School-aged children (6-12 years) typically gain about 3.2 kg (7 lb.) per year in weight and grow roughly 5.8 cm (2.3 in.) in height annually, with expected variations per individual growth patterns.
Step-by-step explanation:
In middle childhood (ages 6-12), children typically experience steady growth. On average, a school-aged child should gain approximately 3.2 kg (7 lb.) per year and grow about 5.8 cm (2.3 in.) in height annually. By the age of 12, the average child is expected to weigh around 41 kg (91 lb.) and measure about 150 cm (59 in.) in height.
It's important to note that there are individual variations in growth patterns, and some children may begin an adolescent growth spurt in pre-adolescence. This information provides a general guideline for expected weight gain in school-aged children.