Article Her Head Covering and Congregational Activities, 4-1-1964 Watchtower, p205-211, par12 (The information might be a bit dated. The artwork certainly is.)
[Head covering needed]
"12 To illustrate: A sister who conducts the congregation Watchtower study or, as has already been mentioned, a congregation book study, should wear a head covering while doing so, as should a sister who offers prayer at such meetings, and they would do so even though being seated at the time.
"In most cases where a sister presides at a meeting with her head covered the number in attendance is quite small, and it would normally not be necessary for her to stand while conducting. Even at the Watchtower study the attendance may not be more than what is usually to be found at a congregation book study, so those attending can be grouped around in a similar way to that of such a study, and the conductor, while facing the audience, can remain seated in almost all instances.
[Not needed]
"The sister reading the paragraphs can do so from her seat, and, as the one reading, she does not need to have her head covered. The Watchtower is doing the teaching. Even if, due to a larger attendance and with no qualified brother available, the sister had to stand to read in order for all to hear, she would not necessarily have to wear a head coveringsince she is not teaching or presiding at the meeting. She is not giving a talk, only reading a summary from The Watchtower.
[It depends]
"However, here again the sister may prefer to wear a head covering as being suitable for the occasion, and so this would be according to her conscience in the matter. If a sister is wearing a head covering as her normal practice she certainly does not have to remove it at any time while carrying on true worship."
Details, details.

