If a non-Jewish man is in a house with 2 children (aged 2 and 4), is there any problem of Yichud involved for a girl, aged 22, to be in the same house teaching the children?
It is during the day hours and the mother can come home at any time, is this considered Yichud?
If yes, is there anything that can be done to avoid the Yichud problem?
It is an issue of Yichud. However, if the mother can come home at any moment, referred to as Yotze V’nichnas, then it is OK. Likewise, according to many Poskim, if others have the key and can come in unexpectedly, it is also OK. However, both of these Heterim have certain limitations – see in the link below.
Another solution would be to have the door to the street (or to the hallway in a building) open so that others can enter unexpectedly. This applies if it is normal for people to do so.
However, in the latter solution, it only helps if you sit in the room closest to the door.
.ראה מנחת איש פרק כ