I do not think teaching the French version of O Canada to young students is easy as the song is full of imagery that I’m frankly not comfortable teaching quickly to young students. (I would say the same for the English version of O Canada as well).
However, it is our national anthem and I tried to teach it without spending a lot of time explaining every detail that I think Canadians really should reflect upon.
Wiki Kids Search has a great kid/quick classroom friendly translation of Ô Canada.
International Heraldry has the best image I can find with a person with a crown of flowers, a sword and cross.
Mad Beppo has a interesting thread regarding translating French Ô Canada to English.