_____________ are illustrations created on the walls of caves during the Paleolithic Era.
cave paintings
______ is a way of sending sounds or other information through the air. The information is carried by invisible waves.
Radio
________ are an ancient Egyptian writing system that uses pictures and symbols instead of letters and words.
Hieroglyphics
____ is a written message that can be sent to a person, group, or organization. It can be handwritten or printed.
A letter
_________ is a communication system that uses dots, dashes, and spaces to represent letters, numbers, and punctuation.
Morse code
______ is a short electronic message that is usually sent from one cell phone to another.
A text message
_____ is a machine that uses ink to transfer words and images onto paper, cloth, or other materials, to produce printed copies.
A printing press
The ___________ is a set of sentences that represent sounds in written language.
alphabet