North American school calendar versus the Peruvian school calendar
There are two schools in Lima, ICS-Lima and FDR, which operate on the North American calendar (August-June). If your children are transferring from a North American calendar this is an important consideration if you do not want them to lose a year of their education while you serve in Peru. It is difficult to transfer to a Peruvian school following the South American calendar (March-December) without losing a year. When an expatriate arrives in July with a student who has finished grade 4 (in May or June) and are looking at a Peruvian school, their students are already halfway through their school year. Most Peruvian schools would not allow a student to skip half of grade 5 to enroll in grade 5 in August. They would put your child back in grade 4 to finish grade 4 in December. Your child would then start grade 5 in March at the beginning of their new school year. This is especially true if your child is not fluent in Spanish since most of their instruction will be given in Spanish. This means your child loses a half of a year compared to the North American calendar.
When leaving Peru, and transferring back to the North American calendar, your child most likely will lose another half year going through the same process at their new school. Three years later you are leaving Peru in July and your child is halfway through grade 7. When returning to the North American calendar your child will need to either skip half of grade 7 and enter grade 8 or start grade 7 again in August. Many schools will not allow a child to skip a half year and will ask your child to repeat the first half of grade 7. Especially when they do not know what has been taught in the Peruvian system. So even though you have been in Peru for three years, your child has only been given credit for two years of education (grades 5 & 6).