All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu 'alayhi wa sallam, is His slave and Messenger. If this boy has not yet reached the age discernment, then you are not obliged to observe the Hijab in front of him. Ibn Qudaamah said, "As for young boys who have not yet reached the age of discernment, women are not required to veil themselves in front of them." [Al-Mughni]However, when a boy reaches adolescencein other words, when he is nearly fifteen years oldyou should wear the Hijab in front of him. Ahmad ibn Hajar Al-Haythami said:The correct opinion is that an adolescent is a boy who nears the age of maturity. In other words, when he reaches the common age of reaching puberty among his peoplei.e. about fifteen, not nine years old, and perhaps another agethen he is like a mature person, so a woman has to observe the Hijab in front of an adolescent just like she has to observe it in front of an insane mature man. [Tuhfat Al-Muhtaj] There is no sin in looking at his face as long as you do not look at him with lust. 'Aaishah said, "I remember the Prophet, sallallaahu 'alayhi wa sallam, screening me with his upper garment while I was looking at Abyssinians who were playing in the courtyard of the mosque." [Al-Bukhari and Muslim] This wording is that of Al-Bukhari .Allaah Knows best. (Source: islam_web) Classified in Women and Family > Fiqh of Women