Thanks Airballrad! I've always wondered and I'm glad I finally asked!

In Canada, we have Beaver Scouts, which are:

Brown Tails: Kindergarden (5 yrs old)
Blue Tails: Grade One (6 years old)
White Tails: Grade Two (7 years old)
White Tail with Silver Stripes (Magic Light): 8 and almost 8 year olds who are ready to "Swim up" to Cubs, usually at the end of their White Tail year.

Our Cub Scouts are Grades 3 to 5, (or 8, 9 and 10 year olds). Somewhere between ages 10 and 11, they move up to Scouts .