I noticed there were no replies to your question asking for
multicultural lessons for 6th grade. The book Art from Many Hands
might give you some ideas.
Nearly all of my lessons with 6th grade were cultural (or tied in with
social studies). I have some of them on line.
http://www.princetonol.com/groups/iad/lessons/middle/artlessons.htm
Some basic materials can be used for many different cultures. Foil
tooling can be used with Middle East, Egypt, Native
American/Pre-Columbian, African (Nigerian) art lessons. There are many
possibilities. Ceramics bridge nearly all cultures. I taught in
trimesters - each group got different cultural experiences. Weaving
bridges many cultures - some connections have been added to the lesson
plan on IAD.
Let us know what cultures you wish to teach (and what you already do)
and it might be easier for us to come up with new lesson ideas.