Simplify the following text for a Grade 6 native English-speaking person.
Original: Tommy Atkins ( often just Tommy ) is a term for a common soldier in the British Army that was already well established in the nineteenth century , but is particularly associated with World War I. It can be used as a term of reference , or as a form of address .
Simplified: Tommy Atkins ( often just Tommy ) is a term for a common soldier in the British Army . The term was used in the 19th century , but it is particularly associated with World War I. It can be used when talking about the soldiers , or when speaking to them .