All Kinds of Signs Author:Seymour Reith Signs are very useful. Signs are very helpful. Signs are very important to all of us. Let's see how. Signs tell us about doors and stores. Signs tell where we live. — How does a postman know where all the letters go? He matches each address with the right number and street. — Signs tell us what to do and what not to do. — Signs are an aid to ... more »safety. In some cities, there are signs like these. They tell people when it is safe to cross the street. A red flag on the back of a truck is a sign, too. It warns other drivers to be careful....« less