The Cub Scout pack is broken down into smaller groups called Dens.  Boys work on different ranks in Cub Scouting based on their ages.  Scouts learn new skills and build upon those skills to meet new challenges as they get older and advance through the Cub Scout program.
Lion Cubs are our youngest scouts, kindergarten boys.  Lion Cubs serves as a fun, family-oriented introduction to Cub Scouting.  Lion Cubs attend one den meeting and one "Grand Adventure" each month.  Lions are encouraged
to attend pack meetings and events.
Bobcat is the first rank that all scouts who are in first grade, or older, complete prior to receiving the rank for their age.  Lion Cubs begin working on their Bobcat requirements after they graduate to the Tiger Den in the spring of their kindergarten year.
The Tiger Den serves first-grade boys who attend meetings and activities with their adult partner, and work together to complete the requirements of the Tiger Cub badge.
Second-grade boys form the Wolf den.  They attend den meetings on their own, but continue to work on the requirements of their Wolf badge with their families.
Boys in the third grade form the Bear den.  Family involvement is still needed to complete the requirements for the Bear badge, but boys have more choices in their activities and have enough knowledge and skill to take on more of the requirements by themselves.
Boys in fourth and fifth grades become Webelos Scouts.  These scouts complete more advanced activities for their Webelos rank and Arrow of Light requirements.  The advanced activities help prepare boys for their graduation into Boy Scouting.