The state of rest is relative. We can sit still and rest in relation to the chairs. But we are moving relative to a passing car on the street. Also, inside us there are movements of substances, movements of atoms, therefore we cannot be in a state of rest in any way. But if we take the organism as a whole, then it can be in a state of rest relative to other objects. In our case, the boy is at rest relative to the tram window. But with respect to trees and another tram, he is in a state of motion.
One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.