Becky sent in this question:
I understand only an older scout can sign off on rank requirements, but when do the scouts learn the skills and do the items they need? Is it only during scout events?
It is typical for them to learn the skills at meetings and events. Meetings will often involve games and activities which teach or reinforce the skills in the early rank requirements. Campouts and troop outings also provide opportunities for skill instruction.
It is not required that they learn the skills in the troop setting though. If they have the skills necessary to do the requirement as written, then the youth leader should sign it off regardless of where they learned and practiced the skill. They just have to demonstrate the skill or do what the requirement says to do. The requirements must be done as written. No more. No less.
You do have to see if the requirement says something like “under the auspices of the BSA”. In that case, it will matter at what type of event the requirement was fulfilled. See this post from Bryan on Scouting related to that topic.