Is it acceptable for the one who is observing i'tikaaf to teach someone or give a lesson?.
It is better for the one who is observing i'tikaaf to focus on worship by himself such as dhikr, prayer, reading Qur’aan and so on. But if there is a need to teach someone or learn, there is nothing wrong with that, because it is also remembrance of Allaah (dhikr). End quote.
Shaykh Muhammad ibn ‘Uthaymeen (may Allaah have mercy on him)