Show and tell

Show and tell is a common expression. It is about showing an audience something and telling them about it. 
This group exercise is used to teach young children the skills of public speaking. For example, children will bring an item from home and will explain to the class why they chose that certain item, where they got it, and other relevant information.
History.
The modern usage of this term began in the 1940s, but the general concept is older. For example, in one of William Shakespeare's plays, a character uses the same words to link something with words explaining it'