We do Cub scouts (I"m a Wolf den leader).
Tiger cubs = first grade or age 7
Wolf = second grade or age 8
Bear = third grade or age 9
Webelos I = 4th grade or age 10
Webelos II = 5th grade or age 11
If you are homeschooled, it can be what grade your parent says you are in.
However, I would suggest going closely with your agemates. The activities can require physical dexterity (making involved art projects, for example), etc. and I think it is more fun if you are with kids near your age.
My son is very gifted, and we have at least one other HG boy in the den.
