Outside of the relationship of a knowledgeable, caring adult with kids - none of it actually matters.

1. The Game
2. Tommy's Tongue
3. WW1 Encyclopedia
4. Great War Curriculum
5. Great War Resources

Y - Yorker

Yank:

American soldier

Yellow Cross:

German Mustard Gas. From the marking painted on the delivery shell casing.

Yellow Parchment:

Leave pass

Yperite:

French name for mustard gas.