Why singular for nez and tête?

Question

I understand why we use the definite article for one and possessive adjective for the other buy why are they both singular?

Accepted Answer

Bonjour Laura,
"...les enfants avaient le nez collé contre la vitre..." + "... un énorme requin scie est passé au-dessus de leur tête".
-> In French, if you were to use the plural, it would sound as if they have several noses/heads each - which would sound rather strange. Instead, we use the singular to express that each child has one nose/head each and they are each different.
The same applies when using the singular form with "leur/leurs". Take a look here and follow the links included in the responses too: leur - leurs
I hope this is helpful.
Bonne journée !

Answer

I'd love to help you, but I don't want to do the entire exercise until I get to the sentence you query about. If you post the sentence here, it's much easier for me to help you.