Horizon,
You need to check out the Scoutmaster's Handbook on the Merit Badge purpose and process.
A part of the purpose is to fulfill a method of Scouting; associating with adults. The responsiblity of a Scout's advancement is his own. The Troop's resposibility is to provide opportunities to learn and practice skills required for advancement.
The process is when a Scout selects a MB he wishes to work on, he goes to his SM. Together, they sit down and select a MBC from the SM's copy of MBC list provided to him by his District Advancement Committee. The Scout fills out a blue
