Question

what do we call children under the age of 1 year?
for teacher use only
toddler
child
infant
baby

Explanation:

According to human growth and development terminology, an infant is specifically defined as a child under 1 year of age. A toddler is typically 1 - 3 years old, "child" is a more general term (can be up to adolescence in some contexts), and while "baby" is a common term, "infant" is the more precise medical/developmental term for under 1 year.

Answer:

Infant