Answer:
The detail from the passage that best supports the conclusion the author draws about teaching in the outdoors is "Their buoyant spirits will not permit them to keep quiet while they are in the open." This implies that teaching in the open air presents a unique challenge because the students are more lively and have difficulty staying focused and quiet. The author goes on to describe the distractions and disruptions that occur when teaching in the open air, such as bugs down collars and boxing matches, which further support the idea that it is more difficult to maintain control and discipline in an outdoor classroom setting.