Quite situational, according to me. No doubt that the statement which you mentioned is accurate, but the other way is also possible, as we can't predict the intentions of the strangers. And that too, the situation is said for the little kids, who are very friendly and believe people easily in most cases. We cannot trust blindly on anyone just because they are soft-spoken and have nice demeanor. As kids will grow up, then they will themselves become able to judge with whom they should talk, and with whom they shouldn't.
Pencil Colors are easier to use than Oil Pastels.