Hello, I take my snakes outside when the weather is at least 70-75 and sunny - they seem to enjoy being outside - I hold them the whole time though.
The longest I would keep it out in the event that you are taking it to a classroom would be a couple hours - they do get stressed with too much activity.
When I take mine anywhere - I bought one of those little suede carriers that are actually made for a little chiwauwa (spelling) dog - it has zippered sides and a clear window - it works our really well. Really though, any container where they can breath and not escape would work.
Good luck with your new bp.